Musnad Ahmad 204:1

Waki’ narrated to us, Ibn Abi Khalid—meaning Isma’il—narrated to us, from his father, who said: I entered upon a man while he was mixing milk with dates. He said: "Draw near, for the Messenger of Allah, may Allah bless him and grant him peace, named them 'the two best things' (al-atyabayn)."