Musannaf Ibn Abi Shaybah 7931 — Those who prayed behind the imam

Abdullah bin al-Sa'ib says: I used to lead the people in the tarawih prayer. While I was praying, I heard the takbir of Sayyiduna Umar (may Allah be pleased with him) at the door of the mosque; he had come to perform Umrah. He entered the mosque and prayed behind me.