Sahih Bukhari
Prophetic Commentary on the Quran (Tafseer of the Prophet (PBUH))
Volume: 006 / Book Number: 060 / Hadith Number: 219
Narrated Ibn Umar:
Allah's Apostle 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 Quran 31:34.")