Charles H. Spurgeon on Psalms 119:111

Thy testimonies have I taken as an heritage for ever. He chose them as his lot, his portion, his estate; and what is more, he laid hold upon them and made them so, taking them into possession and enjoyment. David's choice is our choice. If we might have our desire, we would desire to keep the commands of God perfectly. To know the doctrine, to enjoy the promise, to practise the command, be this a kingdom large enough for me. Here we have an inheritance which cannot fade and cannot be alienated; it is for ever, and ours for ever, if we have so taken it. Sometimes, like Israel at the first coming into Canaan, we have to take our heritage by hard fighting, and, if so, it is worthy of all our labour and suffering; but always it has to be taken by a decided choice of the heart and grip of the will. What God gives we must take.

For they are the rejoicing of my heart. The gladness which had come to him through the word of the Lord had caused him to make an unalterable choice of it. All the parts of Scripture had been pleasing to David, and were so still and therefore he stuck to them, and meant to stick to them for ever. That which rejoices the heart is sure to be chosen and treasured. It is not the head knowledge but the heart experience which brings the joy.

In this verse, which is the seventh of its octave, we have reached the same sweetness as in the last seventh (Psalms 119:103): indeed, in several of the adjoining sevenths, delight is evident. How good a thing it is when experience ripens into joy, passing up through sorrow, prayer, conflict, hope, decision, and holy content into rejoicing! Joy fixes the spirit: when once a man's heart rejoices in the divine word, he greatly values it, and is for ever united to it.