Musnad Ahmad 32:1328

Shababah ibn Sawwar narrated to us, he said: Sulayman informed me, from Thabit al-Bunani, from Anas, who said: "The Messenger of Allah (ﷺ) led us in prayer, and I was with him, as was Umm Sulaym. He placed me to his right, and Umm Sulaym was behind us."