Repentance
Mufti Muhammad Taqi Usmani refers to this ayah while explaining the commitment to not repeat sins. The ayat translates to:
”-and those who, when they happen to commit a shameful act or wrong themselves, remember Allah, then, seek forgiveness for their sins -and who is there to forgive sins except Allah?-and do not persist in what they have done, knowingly.” (3:!35)
Hadhrat explains that once after firm taubah (Taubah tun Nusooh) if one slips again and performs the repented sin, one must hasten to do Taubah with full sincerity and humbleness again, and intend to never commit it in future. (So that he may not be counted among those who became persistent in their sins out of heedlessness, (as mentioned in above ayah,) afterall who is there to forgive sins except Allah SWT!)