Musnad Ahmad 1017:52

Zayd ibn al-Hubab narrated to us, Husayn ibn Waqid narrated to us, Abdullah narrated to me, he said: I heard my father Buraydah saying: I heard the Messenger of Allah, may Allah bless him and grant him peace, saying: "Five [things] no one knows except Allah: 'Indeed, Allah [alone] has knowledge of the Hour and sends down the rain and knows what is in the wombs, and no soul perceives what it will earn tomorrow, and no soul perceives in what land it will die. Indeed, Allah is Knowing and Acquainted.'" [Luqman: 34]