Sayyiduna Tariq bin Shihab (may Allah be pleased with him) said: "The Messenger of Allah (peace and blessings be upon him) used to mention the Hour frequently, until this verse was revealed: 'What concern have you with mentioning it? Its knowledge rests with your Lord alone' [Surah al-Nazi'at: 44]."
Hadith Referenceالمعجم الكبير للطبراني / باب الطاء / 8179