20 and not consider himself better than his fellow Israelites and turn from the law to the right or to the left. Then he and his descendants will reign a long time over his kingdom in Israel.

Read Deuteronomy 17:20 Using Other Translations

That his heart be not lifted up above his brethren, and that he turn not aside from the commandment, to the right hand, or to the left: to the end that he may prolong his days in his kingdom, he, and his children, in the midst of Israel.
that his heart may not be lifted up above his brothers, and that he may not turn aside from the commandment, either to the right hand or to the left, so that he may continue long in his kingdom, he and his children, in Israel.
This regular reading will prevent him from becoming proud and acting as if he is above his fellow citizens. It will also prevent him from turning away from these commands in the smallest way. And it will ensure that he and his descendants will reign for many generations in Israel.