From the additional notes to Charles Spurgeon's The Treasury of David, on Psalm 119
Verses 35-36. Therein do I delight. Incline my heart unto thy testimonies. A child of God hath not the bent of his heart so perfectly fixed towards God but it is ever and anon returning to its old bent and bias again. The best may find that they cannot keep their affections as loose from the world when they have houses, and lands, and all things at their will, as they could when they are kept low and bare. The best may find that their love to heavenly things is on the wane as worldly things are on the increase. It is reported of Pius Quintus that he should say of himself that, when he first entered into orders, he had some hopes of his salvation; when he came to be a cardinal, he doubted of it; but since he came to be pope, he did even almost despair. Many may find a very great change in themselves, much decay of zeal for God's glory, and love to and relish of God's word, and mindfulness of heavenly things, as it fares better with them in the world. Now it is good to observe this before the mischief increaseth. Look, as jealousy and caution are necessary to prevent the entrance and ginning [arousing strong leanings towards] of this mischief, so observation is necessary to prevent the increase of it. When the world doth get too deep an interest in our hearts, when it begins to insinuate and entice us from God, and weaken our delight in the ways of God and zeal for his glory, then we need often to tell you how it is for a rich man to enter into the kingdom of heaven. Thomas Manton.