“Used” means that water is passed over a limb and then drips off it. Used water is not the water from which one scoops; rather, it is the water that drips off after washing with it.

For example, when you wash your face, the water that falls from your face is used water.

If it is used for a recommended purification, such as renewing one’s ablution, the Friday bath, or a second or third washing, it is disliked …

His statement, “for a recommended purification,” means a legislated purification undertaken without a state of ritual impurity.

His statement, “such as renewing one’s ablution”: renewing one’s ablution is sunnah. Thus, if a person prays with his first ablution and then the time for another prayer begins, it is recommended for him to renew his ablution—even though he is already in a state of purity. The water used in this purification remains purifying, but its use is disliked.

It remains purifying because nothing has occurred to remove its purifying quality. It is disliked because of the scholarly disagreement over whether it loses that quality: some scholars held that if it is used for a recommended purification, it becomes pure but no longer purifying. (1) The discussion of reasoning on the basis of scholarly disagreement has already preceded.

His statement, “and the Friday bath”: this is according to the view of the majority, who hold that the Friday bath is sunnah. (2) Thus, if water is used for the Friday bath, it remains purifying, though its use is disliked.

His statement, “and a second and third washing are disliked”: the second and third washings in ablution are not obligatory. The evidence is Allah’s saying: “Wash your faces…” [al-Ma'idah 5:6].