سنن النسائي

It was narrated from Abu Ishaq, that Asim bin Damrah said: "I asked 'Ali bin Abi Talib about the prayer of the Messenger of Allah (ﷺ) during the day before the prescribed prayers. He said: 'Who is able to do that?' Then he told us:'The Messenger of Allah (ﷺ) used to pray two Rak'ahs when the sun had passed its zenith, and four Rak'ahs before the middle of the day, with the Taslim at the end."'