Must one repeat the prayers that were performed with an ablution in which the palms were washed at the beginning, then the forearms from the wrist to the elbow, without pouring water on the ankles when washing the feet, due to ignorance of the ruling?

The relied-upon position in the Hanbali school is that arranging the ablution (wudu') members in order is obligatory. Therefore, the ablution of one who does not observe this order is invalid. However, there is a narration from Ahmad stating that order is not obligatory, and some later scholars adopted this view.

As for the order being waived due to ignorance, the relied-upon position in the madhhab is that it is not waived. However, Shaykh al-Islam Ibn Taymiyyah holds that it is waived due to an excuse, and ignorance is one such excuse.

Accordingly, the ablution in question is valid according to some Hanbalis, and it is permissible to adopt this view, even if it differs from the relied-upon position, especially after the act has occurred and rectification is difficult. Shaykh al-Islam also believes that one who omits a condition or pillar out of ignorance is not required to make it up.