Comentario sobre Pará 12:5

בכנפו – in the corner of his garment. Because the ax that required sprinkling is a primary form of ritual defilement , and when he holds its corner the corner [of the garment] becomes first-degree of ritual impurity, but the person who holds is not impure, for a person and vessels do not receive defilement other than from a primary source of ritual impurity, and even though there is on the ax water sufficient for sprinkling, the person who holds it is not ritually impure because of carrying the waters of lustration, since the Mitzvah had already been fulfilled.

A clean person may hold in the corner of his garment an unclean axe and sprinkle upon it; And even though there is on it enough water for a sprinkling he remains clean. It is possible for a person to hold an axe in his garment, for the axe to be sprinkled upon and for him not to become impure by contact or by carrying the hatat waters. Even though there is enough water to perform the sprinkling, he remains pure because once these waters have purified the axe, their mitzvah has been performed and they no longer defile.

כדי שיטבול ראשי גבעולין ויזה (in order that he may dip the tips of the buds and sprinkle) - outside from what the hyssop absorbs.

How much water is necessary for sprinkling? Sufficient for the tops of the buds to be dipped and for the sprinkling to be performed. Rabbi Judah ruled: they are regarded as though they were on a hyssop of brass. The question is: how much water is necessary to defile one who carries it? According to the first opinion, as long as there is enough water to dip the top buds of the hyssop into the water and to sprinkle some of the water off of them onto the person or thing being sprinkled upon. This quantity of water will defile one who carries it. In other words, there must be enough so that besides that which is absorbed by the hyssop, other water will be sprinkled off. Rabbi Judah rules more stringently. We look at the buds as if they were on hyssop made of brass which doesn't absorb water. As long as there is enough to sprinkle some off of the brass, it is of a sufficient amount to defile. This will be a lower amount than the first opinion.

כאילו הן על האזוב של נחושת – which does not absorb [water]. For we see the waters that are absorbed in the hyssop as if they are discernable/in natural form to complete the measure of sprinkling so that those who carry them are impure. And that which is written (Numbers 19:21): “he who sprinkled the waters of lustration”/"ומזה מי הנדה" [shall wash his clothes and whoever touches the water of lustration shall be impure until evening],” for they (i.e., the Rabbis) expound from this to the person who carries according to the measure of sprinkling, that is as if there were discernable/in natural form that they had the measure of sprinkling. But the Halakha is not according to Rabbi Yehuda.