Musannaf Ibn Abi Shayba 3:5578

Yahya ibn Adam narrated to us, he said: Hammad ibn Zayd narrated to us, from al-Zubayr ibn al-Khirrit, from Abdullah ibn Shaqiq al-Uqayli, he said: We would sometimes pray behind Ibn Abbas in the corner of the mosque, and he would not stand in the middle of it.