It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: I am also a human being. (O Allah) Whomever I have (unknowingly) spoken harshly to, cursed, or struck, make it a means of purification and mercy for that person.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 10435