Al-Hujurat 49:6

Ya ayyuha allatheena amanooin jaakum fasiqun binaba-in fatabayyanoo an tuseebooqawman bijahalatin fatusbihoo AAala mafaAAaltum nadimeen

O you who have believed, if there comes to you a disobedient one with information, investigate, lest you harm a people out of ignorance and become, over what you have done, regretful.

O you who believe, if a sinful person brings you a report, verify its correctness, lest you should harm a people out of ignorance, and then become remorseful on what you did.