﴿ فَأَنجَيْنَٰهُ وَٱلَّذِينَ مَعَهُۥ بِرَحْمَةٍۢ مِّنَّا وَقَطَعْنَا دَابِرَ ٱلَّذِينَ كَذَّبُوا۟ بِـَٔايَٰتِنَا ۖ وَمَا كَانُوا۟ مُؤْمِنِينَ ﴾

“And so, by Our grace, We saved him and those who stood by him, the while We wiped out the last remnant of those who gave the lie to Our messages and would not believe.”

So We delivered him namely Hūd and those with him from among the believers by a mercy from Us and We cut the root of those people who denied Our signs that is We extirpated them and were not believers wa-mā kānū mu’minīna is a supplement to kadhdhabū ‘those who denied’.