What is the ruling on the prayers of one who leaned on a wall during prayer out of ignorance, and what if the leaning was for a short period during one of the prayer's pillars?

It is not permissible for one who is able to stand during an obligatory prayer to lean on a wall or anything else in such a way that he would fall if it were removed; otherwise, his prayer is invalid according to the majority of scholars. As for light leaning, it is disliked (makrooh).

If someone did this out of ignorance, he must repeat the prayer, according to those who deem repetition obligatory for the ignorant person who has violated a pillar or condition.

This ruling applies specifically to obligatory prayers. As for supererogatory (nafilah) prayers, it is permissible to lean during them; indeed, it is permissible to perform them while sitting, and the worshipper receives half the reward of one who stands.