Psalms 119:111

Thy testimonies have I taken as an heritage for ever
The Scriptures, which testify of Christ and of his grace, and of the mind and will of God, are a portion of themselves; and a goodly heritage they are, better than thousands of gold and silver, preferable to all worldly inheritances; as they have been to many, who have forsaken all for Christ and his Gospel. These, like an inheritance, have been transmitted from father to son, from one age of the church to another, in successive generations; nor shall they depart from her, nor from her seed and seed's seed, from henceforth and for ever; they are an inheritance which will continue for ever, ( Deuteronomy 33:4 ) ( Isaiah 59:21 ) . These David chose and took, as for his counsellors, so for his portion and inheritance; and a wise and good choice he made; he chose the good part that should never be taken away; his reason for it follows:

for they are the rejoicing of my heart;
the doctrines in them, the promises of them, when read or heard explained, gave him a sensible pleasure; revived his heart, and cheered his spirits, supported him under all his troubles, and caused him to go on his way rejoicing; see ( Jeremiah 15:16 ) .