If Someone Forgets to Recite Surah al-Fatihah, What Should He Do?

Yunus reports that Hasan was asked about a person who does not recite Surah Al-Fatihah in prayer. He replied that if he recites something other than Surah Al-Fatihah, it is permissible.

Hazrat Hammad says that I asked Ibrahim about the person who forgets to recite Surah Al-Fatiha in prayer but recites another Surah, or recites Surah Al-Fatiha but does not recite any other Surah with it—what is the ruling regarding his prayer? Hazrat Hammad said that his prayer will be valid.

Hazrat Jabir says that Hazrat Amir and Hazrat Hakam were asked about the person who forgets to recite Surah Al-Fatiha in prayer. Hazrat Sha’bi said that he should perform Sajda Sahw, and Hazrat Hakam said that whenever he remembers, he should recite Surah Al-Fatiha at that time.

Hasan, regarding the person who forgets Surah Al-Fatihah but recites Surah Al-Ikhlas, says that his prayer will be valid.