It was narrated from Abu Hurairah (radiyallaahu-anhu) who said: “My Khalil [close friend – i.e. the Messenger of Allaah (Sallal-laahu-alayhi-wasallam)] advised me with three (affairs and) I will not leave them until I die: “To fast three days every month. To offer the Duhaa prayer and to pray the Witr prayer before sleeping”. [Bukhari 1124]