Abu Hurairah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "A man is upon the religion of his friend, so each of you should look at whom he befriends." Ahmad, Tirmidhi, Abu Dawood, Bayhaqi in Shu'ab al-Iman. And Imam Tirmidhi (may Allah have mercy on him) said: This hadith is hasan ghareeb, and Imam Nawawi (may Allah have mercy on him) said: Its chain of narration is authentic. Hasan, narrated by Ahmad, Tirmidhi, Abu Dawood, and Bayhaqi in Shu'ab al-Iman.