Joshurun, i.e. Israel, as is agreed by Christian and Jewish interpreters, whom he calls right, or upright, or righteous, (as the word signifies,) not that they were so indeed, but partly by way of instruction, to mind them what they professed, and promised, and ought to be; and partly by way of exprobration, to show them how unlike they were to the people of God, which they pretended to be, and what a shame it was to them to degenerate so much from their their name and profession. Waxed fat, and kicked, as well-fed and wanton cattle used to do; he grew insolent and rebellious against God, and against his word and Spirit. Thou art covered with fatness; which is here rightly understood and supplied, by comparing this place with Job 15:27 Psalms 17:10.
Related Commentaries of Deuteronomy 32:15
Deuteronomy 32:15
15 But Jeshurun waxed fat, and kicked: thou art waxen fat, thou art grown thick, thou art covered with fatness; then he forsook God which made him, and lightly esteemed the Rock of his salvation.