שמר את כל המצוה — The word שמור is a frequentative present tense, gardant in old French, keeping in English

והקמת לך THEN THOU SHALT RAISE THEE UP [GREAT STONES] — in the Jordan, and afterwards you shall take out from there others and build an altar of them on Mount Eval. Consequently you must say that there were three sets of stones: twelve in the Jordan, an equal number in Gilgal, and another twelve on Mount Ebal, as is stated in Treatise Sotah 35b.

באר היטב EXPLAINING THEM WELL — i.e. in seventy languages (Sotah 32a; cf. Rashi on Deuteronomy 1:5).

הסכת — Understand this as the Targum does: אצית listen!

היום הזה נהיית לעם THIS DAY YOU HAVE BECOME THE PEOPLE [OF THE LORD YOUR GOD] — On each day it should appear to you as though it were “today” that you have entered the covenant with him (Berachot 63b).

לברך את העם [THESE SHALL STAND UP …] TO BLESS THE PEOPLE — The procedure was as is found in Treatise Sotah 32a: Six tribes ascended the top of Mount Gerizim and the other six the top of Mount Ebal, the priests, the Levites and the Ark remaining below in the midst (i.e. in the valley between). The Levites turned their faces towards Mount Gerizim and began to recite the blessing: “Blessed be the man that does not make any graven or molten image etc.”, and both these and those (the tribes on Mount Gerizim and those on Mount Ebal) answered “Amen”! Then they turned their faces towards Mount Ebal and began to recite the curse, saying: “Cursed be the man who maketh any graven [or molten image]” — and so in the case of all of them (the curses set forth here) till the last: “Cursed be he that does not uphold [all the words of this law to do them]” (cf. Rashi on Deuteronomy 11:29).

מקלה means, “making light of”, it has the same meaning as (Deuteronomy 25:3) “Lest … thy brother become despicable (נקלה).

מסיג גבול [CURSED BE] HE THAT REMOVES [HIS NEIGHBOUR’S] LAND-MARK — i.e. puts it further back in his neighbor’s field and thereby steals ground from him. The word מסיג has the same meaning as the verb in (Isaiah 59:14) “and he is turned backwards (הֻסַּג )".

משגה עור [CURSED BE] HE THAT CAUSES THE BLIND TO GO ASTRAY — This means: one who is blind (inexperienced) in a matter and one gives him bad advice (cf. Rashi on Leviticus 19:14).

מכה רעהו בסתר [CURSED BE] HE THAT SMITETH HIS FELLOW SECRETLY — It is of slander that it here speaks (slander may be termed “smiting in secret”) (Pirkei DeRabbi Eliezer 53). — I have seen in the Work of R. Moses the Preacher; There are here eleven verses beginning with the words “cursed be” corresponding to eleven tribes. In allusion to Simeon, however, he (Moses) did not write down a formula beginning with “cursed be”, because he had no intention to bless him before his death when he blessed the other tribes (the tribe of Simeon is the only one not mentioned in chapter XXXIII. which contains the blessings that Moses bestowed on the tribes), therefore he did not want to curse him either.

אשר לא יקים [CURSED BE] HE THAT DOES NOT UPHOLD [ALL THE WORDS OF THIS LAW TO DO] — Here (in these words) he included the entire Torah under a curse and they took it upon them pledging themselves by an execration and an oath.