Deuteronomy 9:6

“Understand therefore that the Lord thy God giveth thee not this good land to possess it for thy righteousness, etc.] This is again repeated to impress it upon their minds, that it was not for any goodness of theirs, but as a gift of divine goodness to them, that they were put into the possession of the good land, which greatly exceeded any merits of theirs, and was entirely owing to the kindness of God to them, and not to any righteousness of theirs; and this he frequently inculcates, that they might have a thorough understanding of it. And so the doctrines of justification by the righteousness of Christ, and not man’s, and of salvation by the grace of God, and not the works of men, are…”

“Stiff - necked - Rebellious and perverse, and so destitute of all pretence of righteousness. And thus our gaining possession of the heavenly Canaan, must be ascribed to God's power, not our own might, and to God's Grace, not our own merit. In him we must glory. Deuteronomy 9:8”

“9:6 Stubborn (literally stiff-necked) describes a draft animal that is unwilling to bend its neck to the yoke (Exod 32:9; 33:3, 5; Isa 48:4). Sadly, Israel was not just occasionally stubborn; stubbornness was the nation’s characteristic behavior and attitude.”

“Understand: Deu 9:3, Deu 9:4; Eze 20:44 giveth thee: Moses repeats this a third time, that, if it were possible, he might root out of the Israelites the opinion of their own deserts, before God rooted out the Canaanites from their country. a stiffnecked: Deu 9:13, Deu 10:16, Deu 31:27; Exo 32:9, Exo 33:3, Exo 34:9; Ch2 30:8, Ch2 36:13; Psa 78:8; Isa 48:3, Isa 48:4; Eze 2:4; Zac 7:11, Zac 7:12; Act 7:51; Rom 5:20, Rom 5:21 Deuteronomy 9:7”