Is the prostration of forgetfulness (sujud al-sahw) obligatory for me if I omitted two Sunnah acts in prayer, and what is the ruling if I do not perform it?

The statement that whoever omits two sunnahs (recommended acts) of prayer should perform the prostration of forgetfulness (sujud al-sahw) is the view of the Malikis. This prostration is performed before the salam and is recommended, and the prayer is not invalidated by its omission, unless three sunnahs are omitted forgetfully and the prostration is not performed, in which case the prayer becomes invalid. As for the Hanbalis, prostration is not prescribed for omitting sunnahs, whether one or more, but there is no harm if one does prostrate.