Narrated Ibn `Umar:
Allah's Messenger (ﷺ) said, "The keys of Unseen are five which none knows but Allah: None knows what will happen tomorrow but Allah; none knows what is in the wombs (a male child or a female) but Allah; none knows when it will rain but Allah; none knows at what place one will die; none knows when the Hour will be established but Allah." (See The Qur'an 31:34.")
USC-MSA web (English) reference: Vol. 6, Book 60, Hadith 219
Arabic reference: Book 65, Hadith 4697