(33) باب صَلاَةِ الضُّحَى فِي الْحَضَرِ
Narrated Abu Huraira:
My friend (the Prophet) advised me to do three things and I shall not leave them till I die, these are: To fast three days every month, to offer the Duha prayer, and to offer witr before sleeping.
Reference: Sahih al-Bukhari 1178
In-book reference: Book 19, Hadith 56
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 2, Book 21, Hadith 274