The Law Concerning Tithes (Leviticus 27:30-34).
“And all the tithe of the land, whether of the seed of the land, or of the fruit of the tree, is Yahweh's. It is holy to Yahweh.”
That part of the produce of the land which is a tithe is holy to Yahweh. The tithe was one tenth which had originally, while it was relatively sparse in the wilderness, to be set aside for the Levites and priests (see Numbers 18:21; Numbers 18:24). It was their inheritance from Yahweh. Later, in view of the abundance that the land would produce, while still sanctified to Yahweh, the tithe could both be used for a celebratory feast by the producing family as well as in order to provide for the Levites (Deuteronomy 14:22-27; Deuteronomy 15:19-20). Every third year, in ‘the year of tithing', the poor were also to receive a share (Deuteronomy 14:28). A one tenth share of all the produce in the land would amply provide for all three, with the Levites receiving the major part left over after the feasting
“And if a man will redeem aught of his tithe, he shall add to it the fifth part of it.”
But if for some reason a man wished to retain part of what he would normally give as a tithe he must redeem it by paying its value plus one fifth.
“And all the tithe of the herd or the flock, whatever passes under the rod, the tenth shall be holy to Yahweh.”
This does not, however, apply to the tithe of the herd or the flock. The Levites would be present to ensure that proper tithes were being paid, and in the case of herd and flock would pass them under a rod, taking aside every tenth one. That was then holy to Yahweh.
“He shall not search whether it be good or bad, neither shall he change it: and if he change it at all, then both it and that for which it is changed shall be holy; it shall not be redeemed.”
Once this was done a man could not change any of these animals for another. He cannot check whether the ones set aside for celebratory feasts or for the Levites are better or worse than the others. The choice was irrevocable. If in fact he does seek to change one then both the one being changed, and the one changed for it are both holy to Yahweh, and so he loses out financially. This may for example have been done in order to ensure that at the family feast at the Central Sanctuary the best was available for them to eat.
“These are the commandments, which Yahweh commanded Moses for the children of Israel in mount Sinai.”
This colophon sums up all the commandments which Yahweh commanded Moses for the children of Israel in Mount Sinai. The content - the commandments listed. The author - Moses from Yahweh. The place - in Mount Sinai. It possibly sums up the whole book. It may, however, just refer to this last chapter.