'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" (JA)
English reference (JA): Book 39, Hadith 270 (JA)
Arabic reference (JA): Book 40, Hadith 286 (JA)