Surah At-Takwir 81:18

وَٱلصُّبْحِ إِذَا تَنَفَّسَ

And by the dawn when it breathes [i.e., stirs]

Translation: Saheeh International

Tafsir

and by the dawn as it breathes as it extends until it becomes broad daylight

Excerpt from Tafsir al-Jalalayn, commentary on 81:18, via Quran.com. The reader has the full commentary and 9 more tafsirs.