Is the prayer of one who does not supplicate between the two prostrations valid, deficient, or void?

The supplication "My Lord, forgive me" (Rabbi ghfir li) between the two prostrations is a recommended sunnah according to the majority of scholars, and neglecting it does not invalidate the prayer. Seeking forgiveness in this position is a sunnah according to the Hanafis, Malikis, and Shafi'is, and it is also a narration from Ahmad. However, what is well-known among the Hanbalis is that it is obligatory, and this is also the view of Ishaq and Dawud. Maintaining the recommended remembrances of prayer is better and brings greater reward.