O Jehovah! the earth is full of thy mercy Here the prophet beseeches God, in the exercise of his infinite goodness, which is reflected in every part of the world, graciously to make him a partaker of the treasure of heavenly wisdom -- a manner of prayer which is very emphatic. When, therefore, he says that the earth is full of God's mercy, it is a kind of earnest entreaty. He not only magnifies the goodness of God, in general, (as he does in other places,) in leaving no part of the world devoid of the proofs of his liberality, and in exercising it not only towards mankind, but also towards the brute creation. What does he then? He desires that the mercy of God, which is extended to all creatures, may be manifested towards him in one thing, and that is, by enabling him to make progress in the knowledge of the Divine law. Whence we gather, that he accounted the gift of understanding as an inestimable treasure. Now if to be endued with the spirit of understanding is a chief token of God's favor, our want of this, proceeding from our own unbelief, is an indication of our alienation from him. It behooves us to remember what we have stated elsewhere, that it is an evidence that we have given ourselves up to the most shameful sloth, when, contented with a superficial knowledge of Divine truth, we are, in a great measure, indifferent about making further progress, seeing so renowned a teacher of the Church labored with the greatest ardor to become more and more acquainted with God's statutes. Besides, it is certain that he does not here treat of external teaching, but of the inward illumination of the mind, which is the gift of the Holy Spirit. The law was exhibited to all without distinction; but the prophet, well aware that unless he were enlightened by the Holy Spirit, it would be of little advantage to him, prays that he may be taught effectually by supernatural influence.

The earth, O Lord, is full of thy mercy - Full of the proofs of thy goodness and compassion. See the notes at Psalm 33:5. This is the expression of a heart full of love to God and to his word. In such a state of mind as the psalmist was in, the goodness of God is seen everywhere. The best preparation for seeing evidence that God is good is a heart full of love. Then the proofs of that love spring up on every side - as when we truly love a friend we find constant proofs of his excellency of character.
Teach me thy statutes - I desire to see more and more of thy law. Thou art so gracious and merciful, the evidence of thy goodness is so widespread round about me, that it leads me to desire to see more and more of thyself and thy law.

The earth is full of thy mercy - What an astonishing operation has the grace of God! In the midst of want, poverty, affliction, and bondage, it makes those who possess it happy! When Christ dwells in the heart by faith, we have nothing but goodness around us. Others may complain; but to us even the earth appears full of the mercy of the Lord.

The earth, O LORD, is full of thy mercy: (e) teach me thy statutes.
(e) For the knowledge of God's word is a singular token of his favour.

The earth, O Lord, is full of thy mercy,.... "Goodness" or "grace" (o); both of the providential mercy and goodness of God, which extends to all his creatures; and of his special grace and goodness to his own people, held forth in his word and ordinances; see Psalm 33:5;
teach me thy statutes: as an instance of mercy, grace, and goodness; see Psalm 119:12.
(o) "gratia tua", Cocceius, Gejerus.

While opposed by the wicked, and opposing them, the pious delight in those who fear God, but, after all, rely for favor and guidance not on merit, but mercy.