Surah Al-Ma'arij — Ayah 4 (70:4)
تَعۡرُجُ ٱلۡمَلَٰٓئِكَةُ وَٱلرُّوحُ إِلَيۡهِ فِي يَوۡمٖ كَانَ مِقۡدَارُهُۥ خَمۡسِينَ أَلۡفَ سَنَةٖ ٤
English translation (Saheeh International)
The angels and the Spirit [i.e., Gabriel] will ascend to Him during a Day the extent of which is fifty thousand years.
Brief commentary
The angels and Gabriel will ascend in them ranks on the Day of Judgement: it is a day of which the duration is fifty thousand years.