Musannaf Ibn Abi Shayba 3:4290

Abu Bakr narrated to us, he said: Ibn ‘Ayyash narrated to us, from Abu Ishaq: I prayed the Asr prayer with my family, then I went out with Ibn al-Aswad. I passed by a mosque in which prayer was being performed. He said, "Enter with us so we may pray." I said, "I have already prayed." He said, "Even if you have."