Riyad-us-Saliheen 367
Abu Hurairah (May Allah be pleased with him) reported: I heard the Prophet (PBUH) saying, "Man follows his friend's religion, you should be careful who you take for friends".
[At-Tirmidhi and Abu Dawud]
This Hadith also induces one to avoid the company of impious people and seek the association of the pious persons.