Surah Al-Muddaththir 74:4

وَثِيَابَكَ فَطَهِّرْ

And your clothing purify.

Translation: Saheeh International

Tafsir

and purify your clothes from impurity or it means shorten them instead of imitating the way in which the Arabs are wont to let their robes drag behind them out of vanity for perhaps they will be sullied by some impurity;

Excerpt from Tafsir al-Jalalayn, commentary on 74:4, via Quran.com. The reader has the full commentary and 9 more tafsirs.