Sahih Muslim
The Book Pertaining to the Excellent Qualities of the Holy Prophet (may Peace be upon them) and His Companions (Kitab Al-Fadail)
Book Number: 030 / Hadith Number: 5841
Anas b. Malik reported that a person came to Allah's Messenger (may peace be upon him) and said: O, the best of creation; thereupon Allah's Messenger (may peace be upon him) said: He is Ibrahim (peace be upon him).