Mishnayos Maaser Sheni Perek 1 Mishnah 2

אין מוכרין אותו – for we derive [through an analogy made – actually היקש – from two verses in close proximity one to the other] גאולה גאולה – derived from חרמים /property set apart for the priest’s or Temple use. It is stated concerning tithes (Leviticus 27:33): “it cannot be redeemed/לא יגאל ,” and it is stated concerning property set apart for the priest’s or Temple use (Leviticus 27:28): “[But of all that anyone owns, be it man or beast or land of his holding, nothing that he has proscribed for the LORD may be sold or proscribed; "לא ימכר ולא יגאל"[every proscribed thing is totally consecrated to the LORD].” Just as there (in the section concerning tithes) it states that the sale is with him, so too here in the case of proscribed property, the sale is with him.

תמים חי – And the same law applies regarding that which is slaughtered, as it says, “nothing…may be…proscribed” and is not sold (see Leviticus 27:28 above), whether living nor slaughtered nor unblemished nor blemished, but an unblemished animal, its fat and its blood are offered on the altar and its meat is eaten by its owners in Jerusalem. But a blemished animal – its owners eat it in every place [other than Jerusalem]. And since the Mishnah needed to teach at the end regarding a first-born animal that we sell it unblemished [and] alive, the Mishnah also teaches at the beginning of an unblemished living [animal] that is alive.

ואין מקדשין בו את האשה – for it is like a sale

הבכור מוכרים אותו תמים חי – because concerning a first-born, it is written (Numbers 18:17): “[But the firstlings of cattle, sheep, or goats] may not be redeemed; [they are consecrated. You shall dash their blood against the altar, and turn their fat into smoke as a gift for a pleasing owner to the LORD],” but they can be sold.

ומקדשין בו את האשה – since it is the money of the Kohen, and it is permissible to sell it.

אסימון – a coin that lacks a shape/form on it, and we do not redeem Second Tithe with it, as it is written (Deuteronomy 14:25): “[you may convert it into money.] Wrap up the money (in your hand) [and take it with you to the place that the LORD your God has chosen],” money that has upon it a shape/form.

ולא על המטבע שאינו יוצא – as it is written (Deuteronomy 14:26): “and spend the money on anything you want [ - cattle, sheep, wine, or any other intoxicant, or anything you may desire…,” except for money that is not current use, for he is not able to purchase with it anything that he wants.

ולא על המעות שאינן ברשותו – such as the case where his purse fell into the Great Sea (i.e., Mediterranean Sea), he is not able to redeem [his] Second Tithe with the monies that are within it, for he must hire someone who sails over the sea to remove it.