Deuteronomy 29:9(10) to 30:20, Isaiah 61:10 to 63:9
Deuteronomy 30:1 affirms the remnant survives even after times of judgment.
Note how often "today" is repeated in chapters 29 and 30!
Tradition claims this scene happened on a Rosh Hashanah, because of verse 30:15 which mentions a "this day" which is both "today" and a day given for repentance.
Note that the Moav part of the Sinai/Moav covenant is entered with an oath (verse 29:11(12)) and no ritual. Extending an already-established covenant does not require additional ritual.
Verse 29:9 says literally "Every bit of you (kulchem) should be before the Lord your God (lifei Adonai Elokeichem)".
The Tz'enah Ur'enah discusses Sanhedrin 10:1 by saying that the phrase "You are standing, today, all of you" in Deuteronomy 29:9 compliments Isaiah 60:19-21 in asserting that all Israel has a portion in the World to Come. The day called "today" in the Deuteronomy passage is claimed to be the transition from darkness to light mentioned in the Isaiah passage.
In verse 29:11 the word "you" in "For you to pass into the covenant of the Lord" is singular, although the rest of the parasha is plural. Each individual enters the covenant. The nation as a single echad enters the covenant.
Verses 29:18-19(19-20) show that someone intentionally sinning does not receive forgiveness when the try what they think is repenting.
Verse 29:28(29) has two interpretations. The "secret things" could be reasons for Torah commandments that are not explicitly given to us. Or the "secret things" could be sins that God sees but no one else sees—and thus God, not a court of people, provides judgment.
In Deut 30:1-14, what is "this commandment" which is also called "it"? Rashi believes that all the Torah's commandments are meant. The Rambam believes that the specific commandment of repentance is meant—and that "in your mouth" means confession, "in your heart" means regret, and "to do them" means redirecting your path.
Verses 30:1-10 contain the word root shoov (turn, repent) seven times. How appropriate as Rosh Hashanah approaches!
The Tz'enah Ur'enah comments on verses 30:6, "In the days of Mashiach, God will cut open the closed hearts and the evil inclination will appear."
God does not honor half-hearted repentance according to verse 30:10.
The Tz'enah Ur'enah concludes its discussion of Parasha Nitzavim with a parable (which I'll paraphrase except for the last line):
Penitents are of five kinds, and may be likened to five kids of people riding on a ship at sea after the ship is beached by a large wave onto a deserted and fruit-laden island.
One type of passanger does not wish to leave the ship, saying, "What if another large way comes and sends the ship away?"
Another group went to the island only for a moment to grab some fresh fruit, and found their places onboard easily.
A third group ate the fruit on the mountain until they heard a shofar sound from aboard and knew their shipmates had seen a second large wave approaching. This group barely made it back to the ship, and in the meanwhile cargo had been put in their places onboard.
The fourth group wandered too far from the ship to hear the shofar. They saw the ship begin to move and ran and swam to get back to it. The barely arrived, and were miserable because of their soaking and extreme exertion. Their places onboard were also gone.
The fifth group was so busy eating fruit that they did not notice the ship leave the island. When winter came this group died.
The ship is our righteousness. Some people are upright and never depart from devotion to God. A second class are those whose evil inclinations cause them to stumble, but only for a moment and then they fully repent. A third group delights in their evil inclinations until they grow old and fear death. Their repentance is also received by God, but they have missed out on God's plans for their lives. The fourth group waits until they are dying to try repentance. This is extremely difficult to do with sincerity, for habitual sinning makes the soul impure. And the fifth group is made up of those who do not repent, dying without repentance, and they reach the fiery depths of Hell.