The Prophet ﷺ said, "A person follows the religion of his close friend, so let each of you consider carefully whom he takes as a close friend."
أن النبي ﷺ قال: الرجل على دين خليله فلينظر أحدكم من يخالل.
Reported by Abu Dawud (4833), Tirmidhi (2378), Ahmad (8028), and Hakim (4/171), all through the route of Zuhayr bin Muhammad, who said, Musa bin Wardan narrated to me, from Abu Hurairah, and he mentioned it. Tirmidhi said, "This is a hasan gharib hadith." Its chain is hasan because of Musa bin Wardan Amiri, their freedman, Abu Umar Misri, who is disputed, but his hadith is hasan when he does not err. Hakim said, "It has also been narrated from Abu Hubab Saeed bin Yasar, from Abu Hurairah," then he reported it through the route of Sadaqah bin Abdullah, from Ibrahim bin Muhammad Ansari, from Abu Hubab Saeed bin Yasar, and said, "The hadith of Abu Hubab is sahih, Allah willing."I say, the first chain is more sahih than this one, though this one strengthens it, despite the weakness present in Sadaqah bin Abdullah and his teacher Ibrahim bin Muhammad Ansari.