Hello, if I usually learn in a shul and the one in charge of the lights asked me to turn off the lights when I leave and I agreed. I ended up forgetting about the lights and came back four hours later. Is that stealing do I need to tell the head rabbi or something. Thank you!
Turning the lights off in the shul when you leave would be saving the shul from a loss, and by turning them off you would fulfill the mitzva of hashovas aveida, which is to help prevent others from incurring a loss. By not turning the lights off you didn’t steal anything from the shul, therefore you didn’t steal anything from the sul and you don’t have to tell the Rabbi anything. If you would like to donate money to the shul, that would be a nice gesture on your part, but you are not obligated to do so.