Musannaf Ibn Abi Shayba 3:673

Abu Khalid al-Ahmar narrated to us, from al-Hasan ibn ‘Amr, from Fudayl, from Ibrahim, from ‘Abdullah, who said: It is as if I am looking at the whiteness of the cheek of the Messenger of Allah (may Allah bless him and grant him peace) when he would say the taslim: "Peace be upon you and the mercy of Allah, peace be upon you and the mercy of Allah."