Musnad Abu Ya'la al-Mawsili 154:8

Muhammad ibn al-Sabbah narrated to us, Sufyan ibn 'Uyaynah narrated to us, from Zayd ibn Aslam, from Ibn 'Umar, who said: The Messenger of Allah (ﷺ) prayed in the Mosque of Quba. Some people from the Ansar came to greet him while he was in prayer, and Suhayb was with him. I asked him, "How did he respond to them?" He said, "He would gesture to them."