Ас-Саффат 37:14

As for reported proofs, their reaction is: وَإِذَا رَ‌أَوْا آيَةً يَسْتَسْخِرُ‌ونَ (And when they see a sign, they make a fun of it - 37:14). It means if they see a miracle that confirms the veracity of his prophethood, and the belief in 'Akhirah ultimately, they ridicule even something so serious and dismiss it by saying that it was nothing but clear magic. Why would they so scoff and jeer? Did they have some basis, some argument in support?

They did and it was: أَإِذَا مِتْنَا وَكُنَّا تُرَ‌ابًا وَعِظَامًا أَإِنَّا لَمَبْعُوثُونَ أَوَآبَاؤُنَا الْأَوَّلُونَ (Is it when we have died and become dust and bones, that we shall be raised again, and even our fathers of a foretime?"- 16-17). In other words, the problem of comprehension that confronted them was as to how in the world could they - once they and their forefathers had become dust and bones - be brought back to life all over again. They were really not willing to admit any proof in this matter, neither that of reason nor that of miracle. Allah Ta’ ala has chosen to answer their question in a single sentence at the end in the words: قُلْ نَعَمْ وَأَنتُمْ دَاخِرُ‌ونَ (Say, "Yes - and you shall be disgraced (too) !" - 37:18)

Outwardly, this is a dismissive answer, as is usually given to rigid people. But, a little deliberation would reveal that it happens to be a full-fledged argument as well. Imam Razi has explained it in Tafsir Kabir. He says: By the rational proof of resurrection given earlier, it already stands established that the rising of human beings once again after death is not something impossible. Then, the rule is that the physical happening of anything rationally possible can be proved on the authority of the statement of someone who is harbinger of nothing but the truth. So, once this much is settled that rising again is possible, then, should some true prophet of Allah simply say thereafter: 'Yes, you shall definitely-rise again," this will be an absolute proof that the said event is bound to happen.