The Sacrifice of Firstborn Animals: 15:19–23 There are several possible reasons why this law is included in this context. One is that the fuller details of the original law (in Exod. 13:11–15; cf. also 22:29f.; 34:19f.; Num. 18:15–18) come in close association with the regulations for the passover, which also follows next in Deuteronomy. Another is that they both have a link in the catchword “firstborn” (since the passover celebrated the sparing of Israel’s firstborn sons on the night of the exodus).

However, another more subtle link with the preceding context lies in the idea of exemption from work. As the slave was to be released from work (“service,” v. 18), so the firstborn ox was not to be put to work (v. 19). The root word is the same in both cases and was also used for Israel’s bonda…