According to John Welch, since the Day of Atonement and the Feast of Tabernacles fell at or around the same time in ancient Israel, it is possible to see influences from both of these holy days upon Benjamin's speech. . . . Leviticus 16:7-10 prescribes the well-known Day of Atonement scapegoat ritual, one of the strongest symbols in the Old Testament of the expiation of sin through the atonement of Jesus Christ. In this ritual, the high priest took two goats, one for Jehovah and the other for Azazel (apparently the name for the prince of the devils). The goat for Jehovah was sacrificed, but upon the other the high priest placed his hands and symbolically transferred to it all the sins of Israel. That scapegoat was then taken into the desert to remove sin from the covenant people of Israel. Perhaps Benjamin had a similar consequence in mind when he said that anyone who did not make and keep God's covenant would be driven away and cast out, as a man would drive out an intruding ass from among his flocks:
And again, doth a man take an ass which belongeth to his neighbor, and keep him? I say unto you, Nay; he will not even suffer that he shall feed among his flocks, but will drive him away, and cast him out. I say unto you, that even so shall it be among you if ye know not the name by which ye are called. (Mosiah 5:14).
Benjamin might have preferred the ass over the goat for several reasons:
1. Availability.
2. For the symbolic value of its fabled stubbornness.
3. From connections between the ass and the Nephites' ancestor Lehi (whose name means "jawbone [of an ass]"--cf. Judges 15:15-17).
4. From connections between the ass and the Nephites' ancestor Joseph (Speiser's translation of Genesis 49:22 sees Joseph as a wild ass colt).
5. Because the ass was uniquely redeemable by the slaying of a lamb (see Exodus 13:13; 24:20). The difference between an ass and goat is not critical; among Israel's neighbors it made little difference what kind of animal was used.
The Rabbis taught that the scapegoat's atonement was effective only when accompanied by repentance. From this developed a tradition of "asking forgiveness of one another on the eve of the Day of atonement." Benjamin likewise implores his people to settle up with their neighbors: to "live peaceably, and to render to every man according to that which is his due," and to "return [any]thing that he borroweth" (Mosiah 4:13,28). [John W. Welch, "The Temple in the Book of Mormon," in Temples of the Ancient World, pp. 352-353, 355-356]