Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates that he heard the Messenger of Allah (peace and blessings be upon him) say: "The keys of the unseen are five," then he (peace and blessings be upon him) recited this verse: "Indeed, with Allah alone is the knowledge of the Hour, and He sends down the rain, and He knows what is in the wombs; and no soul knows what it will earn tomorrow, and no soul knows in what land it will die. Indeed, Allah is All-Knowing, All-Aware" [Surah Luqman: 34].
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13189