Leviticus 27:32

Whatsoever passeth under the rod. — That is, for the purpose of counting and tithing them. The manner in which this was done is described by the Jewish canonists as follows: “The owner is to gather all his lambs or all his calves into the fold and make a little door to it, so that two should not be able to go out at once. He is to place their dams without. As they bleat the lambs hear their voice and go out of the fold to meet them, as it is said, ‘whatsoever passeth under the rod’ (Leviticus 27:32), since it must pass of itself, and not be brought out by his hand. And as they come out of the fold one after another he counts them with the rod, one, two, three, etc., and the tenth which comes out, whether it be male or female, whether it be perfect or blemished, he marks it with a red mark, and says, ‘This is the tithe.’” It is to this custom that the prophet alludes when he says, “I will cause you to pass under the rod, and I will bring you into the bond of the covenant” (Ezekiel 20:37), that is, shall once more claim you, being marked as belonging to the Lord.