Musnad Abu Ya'la al-Mawsili 250:2

'Amr al-Naqid narrated to us, 'Abd al-Ghaffar ibn al-Hakam al-Harrani narrated to us, he said: Yahya ibn al-'Ala' al-Madani—and he is the one who is called al-Razi—narrated to me, from Muhammad ibn Abi Yahya al-Aslami, from Yusuf ibn 'Abd Allah ibn Salam, from his father, who said: I saw the Messenger of Allah, may Allah bless him and grant him peace, take a piece of barley bread, then he took a date and placed it upon it. Then he said: "This is the condiment for this."