Charles H. Spurgeon on Psalms 73:26

My flesh and my heart faileth. They who take the expression in a bad sense, take it to be a confession of his former sin, and to have relation to the combat mentioned in the beginning of the Psalm, between the flesh and the spirit; as if he had said, I was so surfeited with self conceitedness that I presumed to arraign divine actions at the bar of human reason, and to judge the stick under water crooked by the eye of my sense, when, indeed, it was straight: but now I see that flesh is no fit judge in matters of faith; that neither my flesh nor heart can determine rightly of God's dispensations, nor hold out uprightly under Satan's temptations; for if God had not supported me my flesh had utterly supplanted me: My flesh and my heart faileth: but God is the strength of my heart. Flesh is sometimes taken for corrupt nature. Ga 5:13. First, because it is propagated by the flesh (Joh 3:6); secondly, because it is executed by the flesh (Ro 7:25); thirdly, because corruption is nourished, strengthened, and increased by the flesh. 1Jo 2:16. They who take the words in a good sense, do not make them look back so far as the beginning of the Psalm, but only to the neighbour verse. George Swinnock.