Musnad Ahmad 1375

It was narrated that Abu Ishaq said: I heard "Asim bin Damrah say: We asked ‘Ali (رضي الله عنه) about the prayer of the Messenger of Allah (ﷺ) during the day and he said: You cannot do that. We said: Whoever among us is able to do it [will do it]. He said: When the sun was as high there as it is there the time of ‘Asr, he prayed two rak"ahs, When the sun was as high there as it is there at the time of Zuhr, he prayed four rak’ahs. He prayed four rak"ahs before Zuhr and two afterwards, and [he prayed] four rakʻahs before ‘Asr, separating each two rak"ahs with the greeting (tasleem) upon the angels who are close to Allah, the Prophets, and those who follow them of the believers and the Muslims.