On coming before him, I addressed him and said, “I know that you and your companions do not have anything. All of you are in need. It is for this reason that I wish to present some charity to you and your friends.” Rasulullah (sallallahu ‘alaihi wasallam) declined to accept the charity for himself saying, “I do not consume of charity.” He then permitted the Sahaabah (radhiyallahu ‘anhum) to accept it.
Hazrat Salmaan (radhiyallahu ‘anhu) says: I thought to myself, “By Allah! This is one of the three signs (which the aalim of Umooriyyah had mentioned through which the final Nabi can be recognized).”
I then returned home and began to accumulate more wealth. When Rasulullah (sallallahu ‘alaihi wasallam) came to Madinah Munawwarah, then I came to him again and said, “My heartfelt desire is to present something to you. Since you do not accept charity, I have brought this gift for you.” Rasulullah (sallallahu ‘alaihi wasallam) accepted the gift from me. He himself ate from it and he fed his companions from it as well. Seeing this, I thought to myself, “This is the second sign!”
I then returned home, and after a few days, I again presented myself before Rasulullah (sallallahu ‘alaihi wasallam). At that time, Rasulullah (sallallahu ‘alaihi wasallam) had entered the cemetery of Baqee with a janaazah, and a group of the Sahaabah (radhiyallahu ‘anhum) were also with him.
While Rasulullah (sallallahu ‘alaihi wasallam) was sitting among them, I greeted him with salaam. Thereafter, I awoke from where I was, in front of him, and quietly went to sit behind him so that I will be able to see the seal of prophethood (which was the third sign mentioned by the aalim of Umooriyyah).
Observing my behaviour, Rasulullah (sallallahu ‘alaihi wasallam) understood my objective and lifted his shawl from his blessed back. As soon as I saw the seal of prophethood, I recognized it. I stood up, kissed it and began to weep (in extreme joy and happiness).
Rasulullah (sallallahu ‘alaihi wasallam) addressed me and said, “Come in front of me.” I went before him, and just as I am narrating this incident before you, O Ibnu Abbaas, I recounted my entire story to Rasulullah (sallallahu ‘alaihi wasallam) and his Sahaabah (radhiyallahu ‘anhum). In that very noble assembly, I embraced Islam, and Rasulullah (sallallahu ‘alaihi wasallam) was extremely pleased.
After embracing Islam, I remained engaged in the service of my master, and it was for this reason that I was unable to participate in the battles of Badr and Uhud.
(Extracted from Seeratul Mustafa 1/423-424)