Thus, we are commanded to wash the limbs. We wash the face and hands, then the water runs out; by doing so, we have feared Allah to the extent of our ability. We then perform dry ablution in place of wiping the head and washing the feet, because water is unavailable; and by doing so, we have likewise feared Allah to the extent of our ability. There is therefore no contradiction between washing and dry ablution, since both are part of fearing Allah.

Some scholars said that purification with water and dry ablution are not to be combined. Rather, if the available water is enough for half the limbs or more, it is to be used without performing dry ablution; but if it is enough for less than half, the water is not to be used, and one should perform dry ablution only. (1)

They reasoned that combining the two forms of purification entails combining the substitute with that which it replaces, which is invalid because they are mutually contradictory.

They also reasoned that the general rule in the Sacred Law is to give precedence to the greater portion: if the limbs that can be washed constitute the greater portion, one should not perform dry ablution; but if the reverse is the case, then one should perform dry ablution and not wash them.

This was answered by saying that dry ablution here is for the limbs that have not been washed, not for those that have been washed. Thus, it does not entail combining the substitute with that which it replaces. Rather, in some respects it resembles wiping over the leather socks: one washes the limbs that are to be washed and wipes over the sock instead of washing the foot beneath it.

Others said that he should use the water without restriction, for whatever he is able to wash, and not perform dry ablution (708) …..