Musannaf Ibn Abi Shaybah 6106 — What is liked of voluntary prayer

Ibrahim said: The predecessors used to count these rak'ahs as Sunnah: four before Zuhr, two after Zuhr, two after Maghrib, two after Isha and two before Fajr. Ibrahim said: They used to consider two rak'ahs before Asr recommended, but they did not count them as Sunnah.