What to say when fasting 3 days to break oath?

I wonder when you fast for 3 days to take back an oath on not eating something because you realize that thing is in everything. Is there something that has to be recited to make it clear that you take back the oath or do you tell God that you will fast for 3 days because of that cause to take back the oath on that particular thing. Sorry if this sounds complicated, grateful for answer.