Charles H. Spurgeon on Psalms 119:58

I intreated thy favour with my whole heart. A fully assured possession of God does not set aside prayer, but rather urges us to it; he who knows God to be his God will seek his face, longing for his presence. Seeking God's presence is the idea conveyed by the marginal reading, "thy face, "and this is true to the Hebrew. The presence of God is the highest form of his favour, and therefore it is the most urgent desire of gracious souls: the light of his countenance gives us an antepast of heaven. O that we always enjoyed it! The good man entreated God's smile as one who begged for his life, and the entire strength of his desire went with the entreaty. Such eager pleadings are sure of success; that which comes from our heart will certainly go to God's heart. The whole of God's favours are ready for those who seek them with their whole hearts.

Be merciful unto me according to thy word. He has entreated favour, and the form in which he most needs it is that of mercy, for he is more a sinner than anything else. He asks nothing beyond the promise, he only begs for such mercy as the word reveals. And what more could he want or wish for? God has revealed such an infinity of mercy in his word that it would be impossible to conceive of more. See how the Psalmist dwells upon favour and mercy, he never dreams of merit. He does not demand, but entreat; for he feels his own unworthiness. Note how he remains a suppliant, though he knows that he has all things in his God. God is his portion, and yet he begs for a look at his face. The idea of any other standing before God than that of an undeserving but favoured one never entered his head. Here we have his "Be merciful unto me" rising with as much intensity of humble pleading as if he still remained among the most trembling of penitents. The confidence of faith makes us bold in prayer, but it never teaches us to live without prayer, or justifies us in being other than humble beggars at mercy's gate.