For him [i.e., each one] are successive [angels]1 before and behind him who protect him by the decree of Allāh.2 Indeed, Allāh will not change the condition of a people until they change what is in themselves. And when Allāh intends for a people ill,3 there is no repelling it. And there is not for them besides Him any patron.
Translation: Saheeh International (English)
1 Replacing each other by turn.
2 The phrase may also be rendered "...who guard him from [everything except] the decree of Allāh."
3 i.e., punishment or destruction because of their sins.
He, may He be glorified, has angels that come upon a person one after the other. Some of them come at night and some during the day. They protect the person by Allah’s command and they record his statements and actions. Allah does not change the good condition of a people for the worse unless they change the state of gratitude within themselves. When Allah, may He be glorified, wills destruction for a people, then no one can ward off what He wills. You, O people, do not have any one apart from Him who will take charge of your affairs and to whom you can resort to ward off the calamity that afflicts you.