Is it permissible to act upon a fatwa that I recanted from acting upon after I swore not to do so based on it? And is it permissible to act upon a fatwa that I doubted, then became convinced of and acted upon?

If the fatwas differ:

1. If you are capable of examining the evidence: Follow what appears to be more correct and has stronger evidence, while being careful not to pursue concessions or personal whims.

2. If you are among the common folk: Take the fatwa of a scholar whom you trust for their knowledge and piety. If the muftis differ, then follow the one you find most reliable.

If you abandon acting upon a fatwa and then later become convinced of it for a valid reason, there is no harm in acting upon it, as long as it is not a blameworthy pursuit of concessions.

Similarly, there is no harm in breaking an oath if you see something better, and expiation for the oath is obligatory: feeding ten poor persons or clothing them or freeing a slave. If one cannot find these, then fasting for three days.