Hazrat Moulana Ashraf Ali Thanwi (rahmatullahi ‘alaih) once mentioned the following:

The thing which I regard most important for myself, as well as for my friends and associates, is that we refrain from causing any harm to any person in any way.

We should not cause any harm to the next person, regardless of whether the harm is physical e.g. through physical abuse, whether the harm is financial e.g. through usurping someone’s wealth or depriving him of any right, whether the harm is through attacking his honour e.g. by humiliating a person or by making gheebah of him, or whether the harm is emotional e.g. by causing a person anxiety and trauma or dealing with him in an impolite manner, thereby hurting his feelings.

If a person errs in this regard and causes any harm or inconvenience to the next person, then he should not regard it below his dignity to apologize and ask for forgiveness.

(Malfoozaat Hakeemul Ummat 22/125)

Source: Ihyaauddeen.co.za