Musannaf Ibn Abi Shayba 36:314

'Affan narrated to us, he said: Hammad bin Salamah narrated from Thabit, from Anas, that the Quraysh made a peace treaty with the Prophet, may Allah bless him and grant him peace, and among them was Suhayl bin 'Amr. The Prophet, may Allah bless him and grant him peace, said to 'Ali: "Write: In the name of Allah, the Most Gracious, the Most Merciful." Suhayl said: "As for 'In the name of Allah, the Most Gracious, the Most Merciful,' we do not know what 'In the name of Allah, the Most Gracious, the Most Merciful' is. But write what we know: 'In Your name, O Allah.'" The Prophet said: "Write: From Muhammad, the Messenger of Allah." They said: "If we knew that you were the Messenger of Allah, we would have followed you. But write your name and the name of your father." The Prophet, may Allah bless him and grant him peace, said: "Write: From Muhammad bin 'Abdullah." They stipulated to the Prophet, may Allah bless him and grant him peace, that whoever comes to you from us, we will not return him to you, and whoever comes to us from you, you will return him to us. They said: "O Messenger of Allah, will you write this?" He said: "Yes. Indeed, whoever goes from us to them, may Allah distance him, and whoever comes to us from them, Allah will make for him a relief and a way out."