Musannaf Ibn Abi Shayba 3:3592

Abu al-Ahwas narrated to us, from 'Ata' ibn al-Sa'ib, from Maysarah and Zadhan, they said: He used to pray from the voluntary prayers four [rak'ahs] before the noon prayer (Dhuhr), and two [rak'ahs] after it, and two [rak'ahs] after the sunset prayer (Maghrib), and four [rak'ahs] after the night prayer ('Isha'), and two [rak'ahs] before the dawn prayer (Fajr).