Tafsiran Ulangan 29:20: Rashi, Chizkuni, Or HaChaim & Tur HaArokh

הכתובה בספר התורה הזה — Above, however, (Deuteronomy 28:61) it says: And every sickness and every plague … [which is not written] הזאת) בספר התורה הזאת the feminine form, whilst here we have הזה, the masculine)?! But the explanation is: הזאת, the feminine form, refers to the feminine word התורה, whilst הזה, the masculine form, refers to the masculine word הספר in our text. Through the division into clauses by means of the tonic accents (which serve also as marks of interpunctuation) they (the two phrases) are shown to be two different expressions: in the chapter containing the curses (ch. Deuteronomy 28:61) the Tipcha (a disjunctive accent) is placed beneath the word בספר, and the words התורה הזאת are connected one with the other, therefore it says הזאת, the feminine form, (since it has to be connected with a feminine noun), whilst here the Tipcha is placed beneath the word התורה, and consequently the words ספר התורה are connected one with the other (i.e. they form one phrase), — therefore it is a masculine word that is applicable after it, because the term (the pronoun) refers to הספר (which is masculine).

והבדילו, “and the Lord shall separate him, etc;” his punishment will correspond to the principle of the punishment matching the sin. He used his individualism as a way to escape punishment; as a retribution he will be singled out for punishment while G-d is not (yet) dealing with communally committed sins.

ומחה ה׳ את שמו מתחת השמים, "and G'd will blot out his name from under the heaven." Remember that the root of the souls of all the Israelites originates in a sacred part of heaven, immediately below the throne of G'd.