Surah Qaf 50:20

وَنُفِخَ فِى ٱلصُّورِ ۚ ذَٰلِكَ يَوْمُ ٱلْوَعِيدِ

And the Horn will be blown. That is the Day of [carrying out] the threat.

Translation: Saheeh International

Tafsir

And the Trumpet will be blown for resurrection. That namely the day of the blast is the Day of the Promised Threat of chastisement for the disbelievers.

Excerpt from Tafsir al-Jalalayn, commentary on 50:20, via Quran.com. The reader has the full commentary and 9 more tafsirs.