Made an oath on accident

I was about to go to sleep and I was thinking about waking up for Fajr and all of sudden in my head I said “Wallahi I will wake up for Fajr.” I didn’t mean to do it and I didn’t mean the oath.It was on accident. The next night the same thing happened and none of my alarms for Fajr rang so I didn’t wake up. a Do I have to do an expiation? (fast for 3 days)