And it shall be with him, and he shall read it all the days of his life, that he may learn to fear the LORD his God and be careful to observe all the words of this law and these statutes, that his heart may not be lifted above his brethren, that he may not turn aside from the commandment to the right hand or to the left, and that he may prolong his days in his kingdom, he and his children in the midst of Israel.

Deut. 17:19-20 NKJV

What is the effect of daily reading of the Torah?

The king of Israel had to carry with him a Torah scroll at all times and read from it every day of his life in order to be a king according to the Eternal's heart. Moshe Rabbenu teaches us that if the king reads the Torah all the days of his life he will learn to fear the Eternal to keep His commandments by putting them into practice. Besides, daily reading of the Torah will prevent his heart to be lifted above his brothers and from turning from the commandment to the right or left. Thus his life and the life of his children will be long in the kingdom.