Surah At-Tawbah 9:65

وَلَئِن سَأَلْتَهُمْ لَيَقُولُنَّ إِنَّمَا كُنَّا نَخُوضُ وَنَلْعَبُ ۚ قُلْ أَبِٱللَّهِ وَءَايَـٰتِهِۦ وَرَسُولِهِۦ كُنتُمْ تَسْتَهْزِءُونَ

And if you ask them, they will surely say, "We were only conversing and playing." Say, "Is it Allāh and His verses and His Messenger that you were mocking?"

Translation: Saheeh International

Tafsir

And if la-in the lām is for oaths you question them about their mockery of you and of the Qur’ān while they were journeying with you towards Tabūk assuredly they will say making excuses ‘We were only engaging in idle talk and jesting’ in conversation in order to pass the time of the road and we did not mean it. …

Excerpt from Tafsir al-Jalalayn, commentary on 9:65, via Quran.com. The reader has the full commentary and 9 more tafsirs.