Tafsir of As-Saffat 37:12

Nay, you wondered while they mock. means, `you were astounded, O Muhammad, at these people who denied the resurrection whilst you were certain that it is true, when they disbelieved in what Allah told you of this wondrous matter, which is the re-creation of their bodies after they have disintegrated. They oppose what you say because of their intense disbelief and they make fun of what you tell them about that.' Qatadah said, "Muhammad was astounded by the mockery of the misguided ones among the sons of Adam.''

وإذا ذكروا ﻻإ يذكرون