"And if you are astonished, then astonishing is their statement" (the verse). The interpretation of al-Hasan is: If you are astonished, O Muhammad, by their denial of you, then their denial of the Resurrection is more astonishing. And His statement: "Is it that when we are dust, will we indeed be in a new creation?" So their saying that is astonishing.
Surah Ar-Ra'd (6) to the verse (7).
﴿وَإِن تعجب فَعجب قَوْلهم﴾ الآيَةَ، تَفْسِيرُ الْحَسَنِ: إِنْ تَعْجَبْ يَا مُحَمَّدُ مِنْ تَكْذِيبِهِمْ إِيَّاكَ، فتكذيبهم بِالْبَعْثِ أعجب، وَقَوله: ﴿أَئِذَا كُنَّا تُرَابًا أَئِنَّا لَفِي خلق جَدِيد﴾ فَقَوْلهم ذَلِك عجبٌ.
سُورَة الرَّعْد (٦) إِلَى الْآيَة (٧).