The Prophet (saw) said: Whoever conceals the (hidden) fault of his Muslim brother, Allah (SWT) will conceal his faults on the Day of Resurrection. Whoever exposes the fault of his Muslim brother, Allah will expose his faults, until (so that) He shames him, due to it, in his (own) house.
A hadith collected by Ibn Majah, about not exposing people's faults. Allah loves that. If you hide someone's fault Allah will hide your faults in the day of judgment.