Is it obligatory to pay attention to recurring obsessive thoughts regarding purity, intentions, and prayer, knowing that the default state for these is purity?

To get rid of obsessive whispers (waswasah), one must ignore them and pay no attention to them. If Satan whispers that the purification (taharah) or prayer (salat) is invalid, or that something is impure, one should not heed that and should continue with their worship. This is based on the principle that the default state of things is purity, and this purity is not removed except by certain conviction.