What is binding upon me if I swore to fast a day if I did not pray or perform ablution (wudu') from the first time, and I did not do that twice?

One afflicted by obsessive whispering (waswasa) needs to overcome it. Regarding an oath, if only one oath was sworn and its phrasing does not imply repetition, then only one day of fasting is required, unless repetition was intended. The afflicted person is advised to avoid excessive oath-taking and to treat obsessions by relying on Allah.