it is when somebody is repeating what he/she has done for you…in which he/she not suppose to mention it, if it has really been done heartily…
I will give two:
One: if its a mistake and someone s keep on reminding you, Sumbat means reproach or upbraid. Ex: Please stop upbraiding me for my past mistakes. or i cannot think of anything of which i could reproach you for.
Two: If its a favour or help or support and you keep on reminding someone, Sumbat means “Showing it/that to my face.” Example. Please stop showing to my facethat you are the one who helped me get my job now.
the best way is to explain this in context. “Sumbat” is when you constantly nag a person about something you’ve done for him/her in the past and you won’t let him/her forget it.