I used to go to chemistry tutor for help. He teaches 25 or so students, he is a good person but his teaching skills arent that great. I regularly missed exams held by him and this also made my parents a bit angry so one day when i was making dua i said "O Allah i will Attend all of his exams". i attended all his exams after that but now i will be quitting his classes (may join after a month if i cant find any better teacher) my parents understood that he really isnt that good after talking to other parents. they will not be paying the following month so i will not be attending his classes or exams. So do i have to pay kaffarah now? i also want to if i actually made an Oath or a simple promise?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

This wording does not involve any oath or vow, so you are not required to pay an expiation or to do anything else on account of it.

Allaah Knows best.