Musannaf Ibn Abi Shaybah 4047 — Reports on one who forgets to recite

Hammad said: I asked Ibrahim about a man who forgets to recite Surah al-Fatihah in the prayer but recites another surah, or recites Surah al-Fatihah but does not recite another surah with it: what is the ruling on his prayer? Ibrahim said: "His prayer is valid."