Surah Al-Kahf 18:71

فَٱنطَلَقَا حَتَّىٰٓ إِذَا رَكِبَا فِى ٱلسَّفِينَةِ خَرَقَهَا ۖ قَالَ أَخَرَقْتَهَا لِتُغْرِقَ أَهْلَهَا لَقَدْ جِئْتَ شَيْـًٔا إِمْرًا

So they set out, until when they had embarked on the ship, he [i.e., al-Khiḍr] tore it open. [Moses] said, "Have you torn it open to drown its people? You have certainly done a grave thing."

Translation: Saheeh International

Tafsir

So they set off making their way on foot along the coast of the sea until when they embarked on the ship which was carrying them he al-Khidr made a hole in it by destroying a plank or two on the starboard side with an axe after they had sailed into deep waters. …

Excerpt from Tafsir al-Jalalayn, commentary on 18:71, via Quran.com. The reader has the full commentary and 9 more tafsirs.