The 106th prohibition is that we are forbidden from exchanging an animal that has been designated for a sacrifice [with another animal]. This is called Temurah.

The source of this prohibition is G‑d's statement1 (exalted be He), "One may not exchange it nor offer a substitute for it."

This prohibition is mentioned separately2 regarding ma'aser [of cattle].3 The reason [for the apparent repetition] is given in the Sifra: "Ma'aser was already included in the general prohibition. Why did it need to be mentioned separately? In order to compare [the general prohibition] to it: just as ma'aser, for which exchanging is forbidden, is kadshei mizbe'ach,4 so too the only animals that are covered by the prohibition, 'One may not exchange it' are only kadshei mizbe'ach [and not kadshei bedek habayis]."5

One who transgresses this prohibition is punished by lashes.

The details of this mitzvah are explained in tractate Temurah.