What is the ruling on someone who knows the direction of the Qiblah but prayed facing a different direction out of forgetfulness, then remembered that after the prayer? Does he have to repeat the prayer?

According to the Shafi'is and Hanbalis, whoever prays facing a direction other than the Qiblah due to forgetfulness is obligated to repeat the prayer, whether they remember during the prayer time or after it. This is because facing the Qiblah is a condition that is not waived by ignorance or forgetfulness. The Zahiris, on the other hand, hold that the prayer is invalid and must always be repeated by someone who forgot. As for the Malikis, their opinions differed regarding the necessity of repeating the prayer indefinitely or only within its prescribed time. The view of the majority is more preferable for prevalence, because the absence of a condition necessitates the absence of the conditioned.