Musnad Ahmad 462:22

'Attab narrated to us, 'Abdullah—meaning Ibn al-Mubarak—narrated to us, he said: Baqiyyah ibn al-Walid narrated to us, he said: Buhayr ibn Sa'd narrated to us, from Khalid ibn Ma'dan, from al-Miqdam ibn Ma'di Karib, from the Prophet, may Allah bless him and grant him peace, who said: "You must have the pre-dawn meal (suhur), for it is the blessed meal."