The ruling on one who is overtaken by showing off during an act of worship

Question:
If a Muslim performs an act seeking the Face of Allah (Glorified and Exalted is He), and showing off overtakes him after the act has reached its midpoint until the end of the act?

Answer:
If the showing off occurs during the act, it invalidates the act. If it occurs after the act, it does not harm it. If it occurs after the act, once he has been sincere to Allah, he proceeds in his path.
Q: Does it invalidate the entire act if it overtakes it?
A: If it is continuous—such as prayer and its like—the correct view is that it invalidates the act. He prays while showing off, or prostrates while showing off, or the like. However, if it is divisible, such as recitation: the portion of the recitation accompanied by showing off has its reward invalidated, and the portion not accompanied by it is not invalidated. For example, he recites a surah sincerely for Allah, then recites the next surah out of showing off; the reward of the second recitation is invalidated. Likewise, with charity: he gives one hundred out of sincerity, then gives another one hundred out of showing off; the reward of the second is invalidated, because this is divisible. This is unlike prayer, for in prayer, some of it is connected to some of it. Likewise, the fasting of a single day, some of it is connected to some of it.