Umm Salamah, wife of the Prophet ﷺ is reported to have said:
The Messenger of Allah ﷺ said: You will have commanders some of whom you will approve and some of whom you will disapprove. He who expresses disapproval with his tongue (Abu Dawud said : This is Hisham’s version) is guiltless; and he who feels disapproval in his heart, is safe, but he who is pleased and follows them. He was asked; shall we not kill them, Messenger of Allah? Abu Dawud’s version has : Shall we not fight with them? He replied : No, so long as they pray.

حَدَّثَنَا مُسَدَّدٌ، وَسُلَيْمَانُ بْنُ دَاوُدَ، - الْمَعْنَى - قَالاَ حَدَّثَنَا حَمَّادُ بْنُ زَيْدٍ، عَنِ الْمُعَلَّى بْنِ زِيَادٍ، وَهِشَامِ بْنِ حَسَّانَ، عَنِ الْحَسَنِ، عَنْ ضَبَّةَ بْنِ مِحْصَنٍ، عَنْ أُمِّ سَلَمَةَ، زَوْجِ النَّبِيِّ ﷺ قَالَتْ قَالَ رَسُولُ اللَّهِ ﷺ : " سَتَكُونُ عَلَيْكُمْ أَئِمَّةٌ تَعْرِفُونَ مِنْهُمْ وَتُنْكِرُونَ فَمَنْ أَنْكَرَ " . قَالَ أَبُو دَاوُدَ قَالَ هِشَامٌ : " بِلِسَانِهِ فَقَدْ بَرِئَ، وَمَنْ كَرِهَ بِقَلْبِهِ فَقَدْ سَلِمَ وَلَكِنْ مَنْ رَضِيَ وَتَابَعَ " . فَقِيلَ : يَا رَسُولَ اللَّهِ أَفَلاَ نَقْتُلُهُمْ قَالَ ابْنُ دَاوُدَ : " أَفَلاَ نُقَاتِلُهُمْ " . قَالَ : " لاَ مَا صَلَّوْا " .