False oath on Allah

I was in an argument with my sister because I was going to clean our fan with water by turning it off and she told my mother that I was going to clean it without turning it off so I swore an oath of allah that I was not going to do it my intention was to say i was not going to do it without turning it off which is the truth but I don't remember if i said that I was going to do it with the fan off so does that count for a false oath if so does Allah forgive false oath on his name