For the fundamental principle is that it is not obligatory, and the law (Shar') has not prescribed it except in the case of impurity from a dog's licking.
If we hold that seven washings are mandatory, there are two opinions regarding the obligation of [using] earth: One is that it is mandatory, by analogy to the dog's licking. The second is that it is not mandatory, because the Prophet (peace and blessings of Allah be upon him) commanded washing for blood and other things, but did not command the use of earth except in the case of the dog's licking; therefore, it must be restricted to that instance. Furthermore, if earth was commanded as an act of worship (ta'abbudan), it must be restricted to its specific case; and if it was commanded for a reason pertaining to the dog's licking—due to a sticky property therein that is not removed except by earth—then that property is not found elsewhere.
It is recommended to use the earth in the first washing, to comply with the wording of the report, and so that the water may follow it afterward to clean it. Whenever one washes with it, it is sufficient, because it is narrated in a hadith: "One of them with earth." In another hadith: "The first of them." And in another hadith: "In the eighth." This indicates that the placement of the earth among the washings is not intended [as a strict rule].
Section: If the area is affected by multiple impurities that are equal in ruling, they are treated as one impurity. If some are more severe, such as dog's licking combined with another, the ruling follows the more severe one, and the lesser one is included within it.
If one washes the vessel fewer than seven times, then it licks it again, and he then washes it seven times, it is sufficient; for if it is sufficient for an equivalent, it is all the more sufficient for what is lesser.
Section: If one washes the area of the dog's licking (19) and the water from some of the washings touches another area before the completion of seven, there are two opinions regarding it:
One is that it must be washed seven times, which is the apparent meaning of al-Khiraqi's statement and the choice of Ibn Hamid, because it is an impurity, so the ruling of the area it separated from is not taken into account, similar to the impurity of the earth and the place of istinja. The apparent meaning of al-Khiraqi's statement is that it must be washed with earth, even if the area it separated from had already been washed with earth, because it is an impurity that affected something other than the earth, so it resembles the first.
The second is that it must be washed six times if it came from the first [washing], five times from the second, and four times from the third,
(19) In M: "the impurity".