What is the ruling on someone who began an action with the intention of showing off (riyaa') then made his intention sincere for Allah regarding it? And is the invalidation of his action built upon that, or is seeking forgiveness and repentance sufficient for him?

One should not abandon acts of obedience for fear of showing off, rather, one must strive to perform obedience and attain sincerity for Allah the Almighty. Da'wah accounts and tweets are not built from their beginning to their end. If the intention of showing off occurs in them, one must correct the intention and proceed with the act of obedience. Through repentance and seeking forgiveness, the sin of incidental showing off is removed. Acts that are not continuous, such as reading, dhikr (remembrance of Allah), and spreading knowledge, are interrupted by an incidental intention of showing off and require a renewal of intention. If an act began with showing off then became sincere, what was accompanied by sincerity is valid, and what was accompanied by showing off is nullified. One must continue to invite to Allah and be keen on excelling in studies with the intention of benefiting people, spreading knowledge, and defending the religion.