﴿ نَّحْنُ خَلَقْنَٰهُمْ وَشَدَدْنَآ أَسْرَهُمْ ۖ وَإِذَا شِئْنَا بَدَّلْنَآ أَمْثَٰلَهُمْ تَبْدِيلًا ﴾

“[They will not admit to themselves that] it We who have created them and strengthened their make - and [that] if it be Our will We can replace them entirely with others of their kind.”

We created them and made firm their frames their limbs and their joints and whenever We will We can completely replace them with others like them in terms of their created form in place of them by destroying them tabdīlan ‘completely’ is for emphasis; idhā ‘when’ functions in the sense of in ‘if’ similar to where God says in several places in yasha’ yudhhibkum If He will He can take you away cf. Q. 1419; but because He exalted be He has not willed this it has not happened thus far.