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: 5784
Anas (b. Malik) was asked about the old age of Allah's Apostle (may peace be upon him). He said: Allah did not blemish him with white hair.