It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "I have been given the keys of everything except five," namely: "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 / 13287