What is the ruling on someone who performed ghusl and then remembered after finishing that they had not washed one of their limbs, and they had incurred a minor or major impurity? Is it obligatory to repeat the entire ghusl, or is it sufficient to wash only the limb that was not washed?

If a person performs a ritual bath (ghusl) to remove major ritual impurity (hadath akbar) and forgets to wash a limb, their ghusl is valid, and they are only required to wash the forgotten limb. This is because sequential order (tartib) is not a condition for ghusl. Continuity (muwalat) is a Sunnah according to the majority of scholars (Shafi'is and Hanafis), and it is obligatory in Wudu' and a Sunnah in ghusl according to the Hanbalis. As for the Malikis, they consider continuity obligatory in both Wudu' and ghusl, but it is waived by forgetfulness, with the requirement to wash the forgotten limb immediately. If one incurs minor ritual impurity (hadath asghar) before remembering the forgotten limb, they must perform Wudu' for prayer. If they incur major ritual impurity, they must perform ghusl for janabah again.