Charles Ellicott Commentary Leviticus 15:12

"And the earthen vessel, which he that hath the issue toucheth, shall be broken; and every vessel of wood shall be rinsed in water." — Leviticus 15:12 (ASV)

And the vessel of earth ... shall be broken. —For the reason why porous clay vessels must be destroyed when contaminated by defilement, see Leviticus 6:28; Leviticus 11:33. This, however, is the only instance where an earthen vessel touched on the outside was defiled, thus again showing the intense loathing with which the guilt of this kind of infirmity was regarded.

Every vessel of wood shall be rinsed in water. —As these kinds of vessels were both more expensive and more difficult to restore, the Law, which so frequently takes into consideration the circumstances of the people, mercifully spares the more costly utensils. These are to undergo the same baptism as human beings.

The administrators of the law during the Second Temple interpreted the expression “wood” in a more generic sense, as referring to more durable material than clay; hence they included vessels made of copper, brass, silver, etc. Regarding the way in which vessels thus polluted are to be immersed, they ordained that if the utensil is dipped with its mouth downward, or if the vessel, at the time of its immersion, contains any liquid other than water, the baptism is invalid.

Moreover, they ordained that all new vessels which are purchased, or otherwise acquired, must also be immersed, for fear that the maker, or some of those who handled them before the purchase, might have been in a state of defilement.

Hence, orthodox Jews to this day literally baptize cups, plates, knives, forks, or any new utensil which they buy. It is to this law that Christ refers when He says, “And many other things there be, which they have received to hold, as the washing [literally, the baptism] of cups, and pots, brazen vessels, and of tables,” or, as the marginal note more correctly indicates, “beds,” or couches (Mark 7:4).