Peace be upon you. Scholars consider showing off (riyaa) to invalidate all acts of worship, including prayer, fasting, and charity. They stipulate that the intention behind all acts of worship must be free from showing off; if a person intends to show off, the act becomes invalid. It has been reported that the Prophet said, 'I am the best partner; whoever does an action for Me and for someone else, I leave it for the other.' However, we encourage you to reflect on the details provided by scholars regarding showing off that nullifies an action, as there are distinctions and differences among them regarding its categories and implications. Therefore, we advise you to present your question in detail in the jurisprudence section, specifying the nature of the act that involved showing off. For instance, if the showing off occurred in the preliminary actions, such as walking to the mosque rather than being in the mosque itself, this scenario may not invalidate the act. Similarly, if showing off occurred in actions outside of prayer, like adjusting one's attire during prayer, some scholars argue that it does not invalidate the prayer unless it leads back to showing off during the prayer itself. Additionally, it is not considered showing off that a person performs an act sincerely for Allah but enjoys being seen by others. Thus, we recommend detailing the nature of the showing off as mentioned. Regarding your question about repentance, it removes the sin committed by the person, but it does not rectify the invalid action; it must be repeated if it was obligatory. As for the reward for recommended actions performed with the intention of showing off, they are invalid in terms of entitlement, and thus no reward is attached to them even after repentance. However, in terms of divine grace and favor, knowledge belongs to Allah, who is the Most Merciful of the merciful. May you be successful in all good.