Musnad Ahmad 31:35

Muhammad ibn Abi ‘Adi narrated to us, from Sa‘id—meaning Ibn Abi ‘Arubah—he said: Sulayman al-Naji narrated to me, from Abu al-Mutawakkil, from Abu Sa‘id, that the Prophet, peace and blessings of Allah be upon him, prayed with his companions. Then a man came, and the Prophet of Allah, peace and blessings of Allah be upon him, said: "Who will trade with this—or give charity to this—so he may pray with him?" He said: So a man prayed with him. ‘Abd al-Rahman ibn Mahdi narrated to us, he said: Malik narrated to us, from al-Zuhri, from ‘Ata’ ibn Yazid, from Abu Sa‘id al-Khudri, he said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "When you hear the call, say as the caller says." ‘Abdullah said: ‘Abdullah ibn ‘Awn al-Khazzaz and Mus‘ab al-Zubayri narrated it to us, they said: Malik ibn Anas narrated to us, from al-Zuhri, and he mentioned the like of it, exactly.