'Abdullah bin Shaqeeq Radiyallahu'Anhu reports:
"I asked 'Aayesah about the (nawaafil) prayers of Rasulullah Sallallahu 'Alayhi Wasallam?". She replied: "He used to perform two rak'ahs before and two after zuhr. Two after maghrib and two after 'eshaa, and two before fajr" (DE)
English reference (DE): Book 39, Hadith 270 (DE)
Arabic reference (DE): Book 40, Hadith 286 (DE)