Surah Al-Layl 92:2

وَٱلنَّهَارِ إِذَا تَجَلَّىٰ

And [by] the day when it appears

Translation: Saheeh International

Tafsir

and by the day as it unveils as it is revealed and becomes manifest idhā ‘as’ in both instances is an absolute adverbial operated by the verbal action of the oath

Excerpt from Tafsir al-Jalalayn, commentary on 92:2, via Quran.com. The reader has the full commentary and 9 more tafsirs.