It is narrated from Sayyiduna Abu Umamah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said about the verse "They will remain therein for ages" [Surah al-Naba: 23]: "One age is thirty thousand years."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 7926