Charles H. Spurgeon on Psalms 119:36

Incline my heart unto thy testimonies. Does not this prayer appear to be superfluous, since it is evident that the Psalmist's heart was set upon obedience? We are sure that there is never a word to spare in Scripture. After asking for active virtue it was meet that the man of God should beg that his heart might be in all that he did. What would his goings be if his heart did not go? It may be that David felt a wandering desire, an inordinate leaning of his soul to worldly gain, possibly it even intruded into his most devout meditations, and at once he cried out for more grace. The only way to cure a wrong leaning is to have the soul bent in the opposite direction. Holiness of heart is the cure for covetousness. What a blessing it is that we may ask the Lord even for an inclination. Our wills are free, and yet without violating their liberty, grace can incline us in the right direction. This can be done by enlightening the understanding as to the excellence of obedience, by strengthening our habits of virtue, by giving us an experience of the sweetness of piety, and by many other ways. If any one duty is irksome to us it behooves us to offer this player with special reference thereto: we are to love all the Lord's testimonies, and if we fail in any one point we must pay double attention to it. The learning of the heart is the way in which the life will lean: hence the force of the petition, "Incline my heart." Happy shall we be when we feel habitually inclined to all that is good. This is not the way in which a carnal heart ever leans; all its inclinations are in opposition to the divine testimonies.

And not to covetousness. This is the inclination of nature, and grace must put a negative upon it. This vice is as injurious as it is common; it is as mean as it is miserable. It is idolatry, and so it dethrones God; it is selfishness, and so it is cruel to all in its power; it is sordid greed, and so it would sell the Lord himself for pieces of silver. It is a degrading, grovelling, hardening, deadening sin, which withers everything around it that is lovely and Christlike. He who is covetous is of the race of Judas, and will in all probability turn out to be himself a son of perdition. The crime of covetousness is common, but very few will confess it; for when a man heaps up gold in his heart, the dust of it blows into his eyes, and he cannot see his own fault. Our hearts must have some object of desire, and the only way to keep out worldly gain is to put in its place the testimonies of the Lord. If we are inclined or bent one way, we shall be turned from the other: the negative virtue is most surely attained by making sure of the positive grace which inevitably produces it.