What is the ruling on forgetting what was recited in prayer after its completion, and does that affect the validity of the prayer?

If a worshiper finishes his prayer, he is not required to remember what he recited in it or what his Imam recited. Forgetfulness is a human trait for which a person is not held accountable, for even the Messenger of Allah, peace and blessings be upon him, used to forget. There is nothing upon the one who does not remember, after the prayer, what he or his Imam recited.