Say to those who have disbelieved [that] if they cease, what has previously occurred will be forgiven for them. But if they return [to hostility] - then the precedent of the former [rebellious] peoples has already taken place.1
Translation: Saheeh International (English)
1 This is a warning that punishment is always the result of rebellion against Allāh and His messengers.
Say, O Messenger, to those of your people who disbelieve in Allah and His Messenger that if they stop disbelieving in Allah and His Messenger and preventing the believers from Allah’s path, then Allah will forgive their past sins, because Islam wipes out what is before it; but if they return to their disbelief, then Allah’s way of dealing with earlier people has already come as a warning: when they rejected and continued in their disbelief, He swiftly punished them.