Musnad Ahmad 26:703

Waki' narrated to us, Mis'ar narrated to us, from 'Amr ibn Murrah, from 'Abdullah ibn Salamah, from 'Abdullah, who said: "Your Prophet, peace and blessings of Allah be upon him, was given everything except the five keys of the unseen: {Indeed, Allah [alone] has knowledge of the Hour} [Luqman: 34]."