Musannaf Ibn Abi Shayba 3:545

Ishaq ibn Mansur narrated to us, he said: Hureym narrated to us, from Bayan, from Wabarah, he said: I have not seen anyone who found it more difficult for someone to pass in front of him while he was praying than Ibrahim al-Nakha'i and Abd al-Rahman ibn al-Aswad.