Az-Zubair bin al-’Awwam (رضي الله عنه) said:

This verse was revealed when we were present with the Messenger of Allah (ﷺ) : "And fear the Fitnah (affliction and trial) which affects not in particular (only) those of you who do wrong (but it may afflict all the good and the bad people)". (al-Anfal [8:25]). We started saying: “What is this fitnah? And we never thought that it would happen as it did.”