Sayyiduna Salman (may Allah be pleased with him) narrated regarding his acceptance of Islam: When the Prophet (peace and blessings be upon him) came to Madinah, I prepared some food and brought it to the Prophet (peace and blessings be upon him). He (peace and blessings be upon him) asked: "What is this, O Salman?" I said: It is charity. He (peace and blessings be upon him) said to his Companions: "Eat," and he himself did not eat. Then I went back and gathered some food and brought it. He (peace and blessings be upon him) asked: "What is this, O Salman?" I said: It is a gift. He (peace and blessings be upon him) stretched out his hand and ate, and said to his Companions: "Eat."
I said: O Messenger of Allah! Tell me about the Christians. He (peace and blessings be upon him) said: "There is no good in them, nor in the one who loves them." Hearing this, I stood up with a heavy heart. Thereupon Allah, the Mighty and Majestic, revealed this verse: "You will surely find the most intense of people in enmity towards the believers to be the Jews and the polytheists" [Surah al-Ma'idah: 82], up to the verse "overflowing with tears" [Surah al-Ma'idah: 83]. Then the Messenger of Allah (peace and blessings be upon him) sent for me and said: "O Salman! These companions of yours are the ones whom Allah has mentioned."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6096