Deuteronomy 19:21

The lex talionis was to be applied without reserve (see at Exo 21:23; Lev 24:20). According to Diod. Sic. (i. 77), the same law existed in Egypt with reference to false accusers.

The laws which Moses had hitherto been repeating and urging mostly concerned the acts of religion and devotion towards God; but here he comes more fully to press the duties of righteousness between man and man. This chapter relates, I. To the sixth commandment, "Thou shalt not kill" (Deu 19:1-13). II. To the eighth commandment, "Thou shalt not steal" (Deu 19:14). III. To the ninth commandment, "Thou shalt not bear false witness," (Deu 19:15, etc.).

19:21 The legal principle described as life for life is known as lex talionis (“law of retaliation”), according to which the punishment must fit the crime (see Exod 21:23; Lev 24:20); it should be neither too lenient nor too severe. Appropriate punishment is a necessary function of government (cp. Rom 13:1-7), and it served to maintain Israel’s spiritual integrity as God’s people (see study note on Deut 17:7). But vengeance belongs to God, not individuals (see 1 Sam 25:26, 33; Matt 5:38-39; 1 Cor 6:1-8).