What is the ruling on the prayer of one who performed the prostration of forgetfulness (sujūd al-sahw) when their prayer was valid, and must they repeat it?

An increase in the prostrations of forgetfulness, if due to forgetfulness or ignorance, does not invalidate the prayer. However, if it is done intentionally during the prayer, the prayer becomes invalid. If it occurs after the salutation (tasleem), it does not invalidate the prayer, because the increase happened after its completion.