Musannaf Ibn Abi Shaybah

Hazrat Abu Ishaq says that I performed the Asr prayer with my family. Then I went out with Hazrat Ibn Aswad, and we passed by a mosque where prayer was being held. He said, "Let us go into this mosque and pray." I said, "I have already performed the prayer." He said, "Even if you have already prayed, still perform it."