Surah Al-Ma'arij, Verse 4

تَعۡرُجُ ٱلۡمَلَٰٓئِكَةُ وَٱلرُّوحُ إِلَيۡهِ فِي يَوۡمٖ كَانَ مِقۡدَارُهُۥ خَمۡسِينَ أَلۡفَ سَنَةٖ٤

taʿruju l-malāikatu wal-rūḥu ilayhi fī yawmin kāna miq'dāruhu khamsīna alfa sanatin

The angels and the Spirit [i.e., Gabriel] will ascend to Him during a Day the extent of which is fifty thousand years.