How can I atone for the sin of interrupting an obligatory prayer after repeatedly swearing not to interrupt it, knowing that this is due to obsessive doubts and a repentance followed by a return to the sin?

A Muslim should not swear by Allah excessively, as it indicates audacity towards Allah and a lack of reverence for Him. Allah has condemned excessive swearing, as He says: "And do not obey every [habitual] swearer, a disdained ignoble one." The questioner should refrain from excessive swearing and not surrender to the whispers of Satan, but rather turn away from them, rely on Allah, and repent. If the oath was due to obsessive whispers (waswasa) and without intention or will, then nothing is incumbent upon you, as a divorce conditional on waswasa does not take effect, and an oath is more deserving of excuse than divorce. However, if the oath was with intention and will to put an end to thewawas, then expiation (kaffara) is incumbent upon you if you break it.