כי יסתך אחיך בן אמך, “If your brother, son of your mother, will attempt to entice you (to worship an idol);” The reason that the Torah adds the words: “son of your mother,” here is that it is likely that brothers of the same mother, i.e. the same womb, are closer to one another than brothers who only share the same father. Furthermore, sons of only the same father are likely to be hostile to one another for reasons of the eventual inheritance.

בסתר לאמור, “secretly, saying:” the Torah uses an example that is commonplace, i.e. forbidden matters are usually discussed under a mantle of secrecy. Rabbi B’chor shor sees in the Torah’s use here of the expression בסתר, “secretly,” the Torah’s answer to what Solomon said in Proverbs 11,13: הולך רכיל מגלה סוד, “a talebearer reveals secrets,” i.e. condemnation of revealing secrets; there is one exception to his rule and that is when worship of idols is being planned in secret. Then it becomes a positive commandment to reveal the people planning this to the authorities. Verse 9 even adds the fact that concealing such information is equivalent to transgressing a negative commandment also.

כליל לה' אלוקיך, “as a holocaust (completely) to the Lord your G–d.” You are to do this in public so that everyone knows that your motivation is not to enrich yourself by doing so. [According to an opinion in the Talmud, there is no record of this legislation ever having to have been enforced. Ed.]

ונתן לך רחמים, “so that He will show you mercy;” you will be rewarded for not having displayed mercy towards the inhabitants of this city.”