Psalms 43:2

“For thou [art] the God of my strength, etc.] 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and left in a desolate condition by him, and he did not immediately arise to his help and deliverance, and had withdrawn the light of his countenance from…”

“God of my strength--by covenant relation my stronghold (Psa 18:1). cast me off--in scorn. because--or, "in," that is, in such circumstances of oppression.”

“For thou art the God of my strength - See Psalms 18:2, note; Psalms 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 Psalms 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 Psalms 42:9. This expression, with others of a similar character, renders it…”

“43:2 tossed me aside: Other psalms similarly ask whether God has rejected his people (44:9, 23; 60:1, 10; 74:1; 77:7; 88:14; 89:38; 108:11).”

“the God: Psa 28:7, Psa 140:7; Exo 15:2; Isa 40:31, Isa 45:24; Zac 10:12; Eph 6:10; Phi 4:13 why dost: Psa 71:9, Psa 77:7, Psa 94:14; Ch1 28:9 why go: Psa 42:9 Psalms 43:3”