The story of how Salmaan came to Islam is a great story, full of lessons and exhortations. We will let the questioner read the hadeeth in full, so that he might benefit from it: 

It was narrated that ‘Abd-Allaah ibn ‘Abbaas said: Salmaan al-Faarisi told me his story from his own lips. He said: 

I was a Persian man, one of the people of Isbahaan, from a village thereof called Jayy. My father was the chieftain of his village, and I was the dearest of Allaah’s creation to him. He loved me so much that he kept me in his house near the fire, as girls are kept in. I strove hard in the Magian religion until I became the keeper of the fire, which I tended and did not let go out for a moment. My father had a huge garden, and he was busy one day with some construction work, so he said: “O my son, I am too busy with this building today, go and check my garden,” and he told me some of the things he wanted done. I went out, heading towards his garden, and I passed by one of the Christian churches, where I could hear their voices as they were praying. I did not know anything about the people because my father had kept me in his house.

When I passed by and heard their voices, I entered upon them to see what they were doing. When I saw them, I was impressed with their prayer and I was attracted to their way. I said: By Allaah, this is better than the religion that we follow. By Allaah, I did not leave them until the sun set, and I forgot about my father’s garden and did not go there. I said to them: Where did this religion originate? They said: In Syria. Then I went back to my father, who had sent people out to look for me, and I had distracted him from all his work. When I came to him, he said: O my son, where were you? Did I not ask you to do what I asked? I said: O my father, I passed by some people who were praying in a church of theirs, and I was impressed with what I saw of their religion. By Allaah, I stayed with them until the sun set. He said: O my son, there is nothing good in that religion. Your religion and the religion of your forefathers is better than that. I said: No, by Allaah, it is better than our religion. He was afraid for me, and he put fetters on my legs and kept me in his house. I sent word to the Christians saying: If any Christian merchants come to you from Syria, tell me about them. He said: Some Christian merchants came to them from Syria, and they told me about them. I said to them: When they have completed their business and want to go back to their own country, tell me about that. So when they wanted to go back to their own country, they told me about that, and I threw off the irons from my legs and went out with them, until I came to Syria.

When I reached Syria, I said: Who is the best person in this religion? They said: The bishop in the church.  So I went to him and said: I like this religion, and I would like to stay with you and serve you in your church and learn from you and pray with you. He said: Come in. So I went in with him, but he was a bad man. He would command them and exhort them to give charity, but he kept a great deal of it for himself and did not give it to the poor; he had amassed seven chests of gold and silver. I hated him deeply when I saw what he was doing, then he died and the Christians gathered to bury him. I said to them: This was a bad man; he commanded you and exhorted you to give charity, but when you brought it to him he kept it for himself and did not give any of it to the poor. They said: How do you know that? Show us where his treasure is. So I showed them where it was and they brought out seven chests filled with gold and silver. When they saw that they said: By Allaah, we will never bury him; then they crucified him and pelted him with stones. 

Then they brought another man and appointed him in his place. Salmaan said: I have never seen a man who does not offer the five daily prayers who was better than him; he shunned this world and sought the Hereafter and no one strive harder than him night and day. I loved him as I had never loved anyone before, and I stayed with him for a while. Then when he was about to die, I said: O So and so, I was with you and I loved you as I had never loved anyone before, and now the decree of Allaah has come to you as you see; to whom do you advise me to go? What do you command me to do? He said: O my son, by Allaah, I do not know of anyone today who follows what I followed. The people are doomed; they have changed and abandoned most of what they used to follow, except for a man in Mosul. He is So and so, and he follows what I used to follow, so go and join him. When he died and was buried, I went to the man in Mosul. I said to him: O So and so, So and so advised me when he died to come to you, and he told me that you follow the same as he followed. He said to me: Stay with me. So I stayed with him, and I found him to be a good man who followed the same as his companion had followed. But soon he died. When he was dying I said to him: O So and so, So and so advised me to come to you and told me to join you, but now there has come to you from Allaah what you see. To whom do you advise me to go? What do you command me to do? He said: O my son, by Allaah I do not know of anyone who follows what we used to follow except a man in Nasayyibeen. He is So and so; go to him. When he died and was buried, I went to the man in Nasayyibeen. I came to him and told him my story and what my companion had told me to do. He said: Stay with me. So I stayed with him and I found him to be a follower of the same way as his two companions, and I stayed with a good man. By Allaah, soon death came upon him, and when he was dying I said to him: O So and so, So and so advised me to go to So and so; then So and so advised me to come to you. To whom do you advise me to go and what do you command me to do? He said: O my son, by Allaah we do not know of anyone left who follows our way and to whom I can tell you to go, except a man in ‘Ammooriyyah. He follows something like what we follow. If you wish, go to him, for he follows our way. When he died and was buried, I went to the man in ‘Ammooriyyah and told him my story. He said: Stay with me. So I stayed with a man who was following the same way as his companions.

I earned wealth until I had cows and sheep, then the decree of Allaah came to him. When he was dying I said to him: O So and so, I was with So and so, and So and so told me to go to So and so; then So and so told me to go to So and so; then So and so told me to come to you. To whom do you advise me to go and what do you command me to do? He said: O my son, by Allaah, I do not know of anyone who follows our way to whom I can advise you to go. But there has come the time of a Prophet, who will be sent with the religion of Ibraaheem. He will appear in the land of the Arabs and will migrate to a land between two harrahs (lave fields; land with black rocks), between which there are palm trees. He will have characteristics that will not be hidden. He will eat of what is given as a gift but he will not eat of what is given as charity. Between his shoulder blades is the Seal of Prophethood. If you can go to that land then do so. Then he died and was buried, and I stayed in ‘Ammooriyyah as long as Allaah willed I should stay, then some merchants of Kalb passed by me and I said to them: Will you take me to the land of the Arabs and I will give you these cows and sheep of mine? They said: Yes. So I gave them the cows and sheep, and they took me there, but when they brought me to Waadi al-Qura they wronged me and sold me as a slave to a Jewish man.

When I was with him I saw the palm trees, and I hoped that this was the land that my companion had described to me, but I was not sure. Whilst I was with him, a cousin of his from Banu Qurayzah came to him from Madeenah, and he sold me to him, and he took me to Madeenah. By Allaah, as soon as I saw it, I recognized it from the description given to me by my companion.  I stayed there, and Allaah sent His Messenger, who stayed in Makkah as long as he stayed, and I did not hear anything about him because I was so busy with the work of a slave. Then he migrated to Madeenah, and by Allaah, I was at the top of a palm tree belonging to my master, doing some work on it, and my master was sitting there. Then a cousin of his came and stood beside him, and said: May Allaah kill Banu Qaylah! By Allaah, right now they are gathering in Quba’ to welcome a man who has come from Makkah today, and they say that he is a Prophet. When I heard that, I began to shiver so much that I thought I would fall on top of my master. I came down from the tree and started saying to that cousin of his: What are you saying, what are you saying? My master got angry and he struck me with his fist and said: What has it got to do with you? Go back to your work! I said: Nothing; I just wanted to make sure of what he was saying.

I had something that I had collected, and when evening came, I went to the Messenger of Allaah (peace and blessings of Allaah be upon him) when he was in Quba’, and I entered upon him and said to him: I have heard that you are a righteous man and that you have companions who are strangers and are in need. This is something that I have to give in charity, and I see that you are more in need of it than anyone else. I brought it near to him and the Messenger of Allaah (peace and blessings of Allaah be upon him) said to his companions: “Eat,” but he refrained from eating.  I said to myself: This is one. Then I went away and collected some more. The Messenger of Allaah (peace and blessings of Allaah be upon him) moved to Madeenah, then I came to him and said: I see that you do not eat (food given in) charity; this is a gift with which I wish to honour you. The Messenger of Allaah (peace and blessings of Allaah be upon him) ate some of it and told his companions to eat too. I said to myself: This is two. Then I came to the Messenger of Allaah (peace and blessings of Allaah be upon him) when he was in Baqee’ al-Gharqad, where he had attended the funeral of one of his companions and he was wearing two shawls and was sitting among his companions. I greeted him with salaam then I moved behind him, trying to look at his back to see the Seal that my companion had described to me. When the Messenger of Allaah (peace and blessings of Allaah be upon him) saw me going behind him, he realized that I was trying to find confirmation of something that had been described to me, so he let his rida’ drop from his back, and I saw the Seal and recognized it. Then I embraced him, kissing (the Seal) and weeping, and the Messenger of Allaah (peace and blessings of Allaah be upon him) said to me: “Turn around.” So I turned around and I told him my story as I have told it to you, O Ibn ‘Abbaas. The Messenger of Allaah (peace and blessings of Allaah be upon him) wanted his companions to hear that.

Then Salmaan was kept busy with the work of a slave, until he had missed attending Badr and Uhud with the Messenger of Allaah (peace and blessings of Allaah be upon him). He said: Then the Messenger of Allaah (peace and blessings of Allaah be upon him) said to me: “Draw up a contract of manumission, O Salmaan.” So I draw up a contract of manumission with my master in return for three hundred palm trees which I would plant for him, and forty uqiyahs. The Messenger of Allaah (peace and blessings of Allaah be upon him) said to his companions: “Help your brother.” So they helped me with the palm trees, one man gave thirty small trees and another gave twenty, and another gave fifteen, and another gave ten, i.e., each man gave according to what he had, until they had collected three hundred small trees for me. Then the Messenger of Allaah (peace and blessings of Allaah be upon him) said to me: “Go, O Salmaan, and dig the holes where they are to be planted. When you have finished, come to me and I will plant them with my own hand.” So I dug the holes for them, and my companions helped me, then when I had finished, I came to him and told him. The Messenger of Allaah (peace and blessings of Allaah be upon him) came out with me and we started to bring the trees close and the Messenger of Allaah (peace and blessings of Allaah be upon him) planted them with his own hand. By the One in Whose hand is the soul of Salmaan, not one single tree among them died. So I had paid off the trees but there still remained the money. A piece of gold the size of an egg was brought to the Messenger of Allaah (peace and blessings of Allaah be upon him) from one of his campaigns. He said: “What happened to the Persian who had a contract of manumission?” I was summoned to him and he said: “Take this and pay off what you owe, O Salmaan.” I said: How could this pay off everything I owe, O Messenger of Allaah? He said: “Take it, and Allaah will help you to pay off what you owe.” So I took it and weighed it for them, and by the One in Whose hand is the soul of Salmaan, it was forty uqiyahs, so I paid them their dues and I was set free. I was present with the Messenger of Allaah (peace and blessings of Allaah be upon him) at al-Khandaq, and after that I did not miss any major event with him. 

Narrated by Ahmad in al-Musnad (5/441). The scholars of hadeeth said: Its isnaad is hasan.