What about someone afflicted by the evil eye and severe obsessive thoughts, who used to swear frequently and break oaths during that period?

A Muslim must not surrender to obsessive whispering (waswasah) in worship, because it is a trick from Satan to divert righteous people and cut them off from their Lord. A Muslim should say "Lā ilāha illallāh (There is no god but Allah)" when feeling waswasah, because Satan retreats and distances himself upon hearing dhikr (remembrance of Allah), and "Lā ilāha illallāh" is the head of dhikr.