Narrated Mu'adh ibn Anas: The Prophet (ﷺ) said: If anyone guards a believer from a hypocrite, Allah will send an angel who will guard his flesh on the Day of Resurrection from the fire of Jahannam; but if anyone attacks a Muslim saying something by which he wishes to disgrace him, he will be restrained by Allah on the bridge over Jahannam till he is acquitted of what he said

English translation · Sunan Abu Dawud