What is the ruling on forgetting to recite a verse or mispronouncing a word during prayer and remembering it during bowing (rukuʿ), prostration (sujud), or after the prayer, and is it obligatory to repeat the rakʿah?

The obligatory part of recitation is Al-Fatihah. Reciting an additional verse or two, or substituting one verse for another, does not invalidate the prayer. However, it is sunnah to recite some verses along with Al-Fatihah in the first two rak'ahs of the prayers. Al-Fatihah alone is sufficient in the third rak'ah of Maghrib, and the third and fourth rak'ahs of Dhuhr, 'Asr, and 'Ishaa'.