For thou art the God of my strength - See Psalm 18:2, note; Psalm 28:7, note.

Why dost thou cast me off? - As if I were none of thine; as if I were wholly abandoned. Compare the notes at Psalm 22:1. The word rendered "cast off" - זנח zânach - is a word which implies strong disgust or loathing: "Why dost thou cast me off as a loathsome or disgusting object?" Compare Revelation 3:16. The Hebrew word means properly to be foul, to be rancid, to stink: then, to be loathsome or abominable; and then, to treat or regard anything as such. Compare Hosea 8:3, Hosea 8:5; Isaiah 19:6.

Why go I mourning ... - See the notes at Psalm 42:9. This expression, with others of a similar character, renders it morally certain that this psalm was composed by the same person, and with reference to the same circumstances, as the former.

For those art the God of my strength - The psalmist speaks here, as in other places in the person of the whole Israelitish people then captive in Babylon. We still acknowledge thee for our God. Why are we cast off? Now that we are humbled and penitent, why are we not enlarged? Why are we not saved from this oppression of the Babylonians?

For thou art the God of my strength,.... Who being the strong and mighty God was able to deliver and save him, as well as to plead his cause; and was the author and giver of strength, natural and spiritual, to him; and was the strength of his heart, life and salvation; and is a good reason why he committed his cause unto him;

why doest thou cast me off? this is the language of unbelief: it being what was not in reality, only in appearance: the psalmist was ready to conclude he was cast off and rejected of God, because he was afflicted and left in a desolate condition by him, and he did not immediately arise to his help and deliverance, and had withdrawn the light of his countenance from him; but God does not cast off or reject any of his people; they always continue in his love, and in his covenant, and in the hands of his Son; they are always in his sight and family, and shall never perish eternally; and whoever casts them off, or casts them out, he will not;

why go I mourning because of the oppression of the enemy? See Gill on Psalm 42:9.

For thou art the God of my strength: why dost thou cast me off? why go I mourning because of the oppression of the enemy?

2. God of my strength-by covenant relation my stronghold (Ps 18:1).

cast me off-in scorn.

because-or, "in," that is, in such circumstances of oppression.

43:6-11 The way to forget our miseries, is to remember the God of our mercies. David saw troubles coming from God's wrath, and that discouraged him. But if one trouble follow hard after another, if all seem to combine for our ruin, let us remember they are all appointed and overruled by the Lord. David regards the Divine favour as the fountain of all the good he looked for. In the Saviour's name let us hope and pray. One word from him will calm every storm, and turn midnight darkness into the light of noon, the bitterest complaints into joyful praises. Our believing expectation of mercy must quicken our prayers for it. At length, is faith came off conqueror, by encouraging him to trust in the name of the Lord, and to stay himself upon his God. He adds, And my God; this thought enabled him to triumph over all his griefs and fears. Let us never think that the God of our life, and the Rock of our salvation, has forgotten us, if we have made his mercy, truth, and power, our refuge. Thus the psalmist strove against his despondency: at last his faith and hope obtained the victory. Let us learn to check all unbelieving doubts and fears. Apply the promise first to ourselves, and then plead it to God.