What does the imam do if he forgets al-Fatihah in the first rak'ah of a secret prayer?

Question:
May Allah bless you. This person asks, may Allah preserve you: An imam forgot to recite al-Fatihah in the first rak'ah of a secret prayer. What should he do, and what is the ruling regarding his prayer?

Answer:
If he has not yet bowed, he should recite al-Fatihah and then recite whatever is easy for him, then bow and prostrate for forgetfulness. However, if he did not remember until after he had completed the rak'ah, that rak'ah is invalid, and the next rak'ah takes its place, becoming the first one. He then completes his prayer and prostrates for forgetfulness. This applies if he is an imam or praying alone. As for if he is a ma'mum, the imam's recitation suffices for the ma'mum. Yes.