Surah As-Saffat 37:12

Those who set the Ranks · Verse 12 of 182 · Juz 23 · Page 446

بَلْ عَجِبْتَ وَيَسْخَرُونَ

But you wonder, while they mock,

Translation: Saheeh International

Tafsir

Nay but bal is for effecting a transition from one object to another which in this case is to inform of his state and theirs you marvel ‘ajibta addressing the Prophet s that is you marvel that they deny you while they engage in ridicule at your marvelling

Excerpt from Tafsir al-Jalalayn, commentary on 37:12, via Quran.com. The reader has the full commentary and 9 more tafsirs.