Второзаконие 27:22

III. Third Discourse, or Renewal of the Covenant - Deuteronomy 27-30 The conclusion of the covenant in the land of Moab, as the last address in this section (ch. 29 and 30) is called in the heading (Deu 29:1) and in the introduction (Deu 29:9.), i.e., the renewal of the covenant concluded at Horeb, commences with instructions to set up the law in a solemn manner in the land of Canaan after crossing over the Jordan (ch. 27). After this there follows an elaborate exposition of the blessings and curses which would come upon the people according to their attitude towards the law (ch. 28). And lastly, Moses places the whole nation with a solemn address before the face of the Lord, and sets before it once more the blessing and the curse in powerful and alarming words, with the exhortation to choose the blessing and life (ch. 29 and 30).

Moses having very largely and fully set before the people their duty, both to God and one another, in general and in particular instances, - having shown them plainly what is good, and what the law requires of them, - and having in the close of the foregoing chapter laid them under the obligation both of the command and the covenant, he comes in this chapter to prescribe outward means, I. For the helping of their memories, that they might not forget the law as a strange thing. They must write all the words of this law upon stones (Deu 27:1-10). II. For the moving of their affections, that they might not be indifferent to the law as a light thing. Whey they came into Canaan, the blessings and curses which were the sanctions of the law, were to be solemnly pronounced in the hearing of all Israel, who were to say Amen to them (v. 11-26). And if such a solemnity as this would not make a deep impression upon them, and affect them with the great things of God's law, nothing would.

27:22 whether . . . the daughter of his father or his mother: Though this instruction concerns a relationship with a half sister or foster sibling, it precludes a sexual relationship with one’s full sibling as well (see Lev 18:9; 20:17).