What is the ruling on washing only one foot before putting on the leather sock?

Primary text

It is not permissible to wipe if one washes only one foot and puts that foot into the sock, and then washes the other foot and puts it into the other sock. This is the position of Shafi'i and Ishaq, and similar views are attributed to Malik. The justification is that the prerequisite is the existence of purity in both feet at the time of putting on the socks, and the lack of complete purity in one foot invalidates the condition. Furthermore, that for which purity is required demands complete purity, like prayer or touching the Mus'haf.