When the angel descended to bring the two mountains together upon the people of Ta'if, was that not unjust, especially since those who harmed the Messenger of Allah, may Allah bless him and grant him peace, were only some of the people of Ta'if and not all of them?

It is not permissible for a Muslim to utter the phrase, "Why does Allah punish everyone, even though the act was committed by only some of them?" This is because Allah, the Almighty, is the Just Judge who has forbidden injustice upon Himself, and He can never wrong anyone.

An act may be committed by some people, and others may approve of it or incite it, thus becoming partners with the doer in sin. An example of this is the story of Prophet Salih's she-camel, which was hamstrung by one person, but others approved of it, so Allah became wrathful with them and encompassed them all with punishment.

If people abandon enjoining good and forbidding evil and striving for reform, punishment may afflict everyone, as Allah Almighty says: {And fear a trial which will not afflict those who have wronged among you exclusively} (Quran 8:25). And as the Messenger of Allah, peace and blessings be upon him, said: "Shall we be destroyed while there are righteous people among us?" He replied: "Yes, if wickedness becomes widespread." If there are reformers among them, Allah saves the reformers and then sends down punishment upon the rest.