Deuteronomy 17:20

20 So that his heart may not be lifted up over his countrymen, and he may not be turned away from the orders, to one side or the other: but that his life and the lives of his children may be long in his kingdom in Israel.

Deuteronomy 17:20 Meaning and Commentary

Deuteronomy 17:20

That his heart be not lifted up above his brethren
On account of his office, the dignity of it, considering that he was subject to the law of God, and accountable to the Lord for all his actions:

and that he turn not aside from the commandment, to the right hand or
to the left;
not in the least deviate from the law of God in the whole of his conduct, and particularly in the exercise of his kingly office:

to the end that he may prolong his days in his kingdom;
ruling well according to the laws of God being the way to rule long:

he and his children in the midst of Israel;
this shows, as Jarchi observes, that if his son was fit for the kingdom, he was to be preferred to any other man; for though it was elective, yet to be continued in the same family, provided they walked in the ways of the Lord, and observed his laws.

Deuteronomy 17:20 In-Context

18 And when he has taken his place on the seat of his kingdom, he is to make in a book a copy of this law, from that which the priests, the Levites, have in their care:

19 And it is to be with him for his reading all the days of his life, so that he may be trained in the fear of the Lord his God to keep and do all the words of this teaching and these laws:

20 So that his heart may not be lifted up over his countrymen, and he may not be turned away from the orders, to one side or the other: but that his life and the lives of his children may be long in his kingdom in Israel.