Musnad Abu Ya'la al-Mawsili 152:85

Abu Khaythama narrated to us, Jarir narrated to us, from al-A'mash, from 'Amr ibn Murrah, from 'Abdullah ibn Salamah, who said: I heard 'Abdullah say: Your Prophet has been given the knowledge of everything, except for the keys of the five [things]: "Indeed, Allah [alone] has knowledge of the Hour and sends down the rain and knows what is in the wombs," [reciting] the entire verse.