The words of the text describe three states which are, or have been, or will be all ours.
I. The first state is thus described: "In my prosperity I said, I shall never be moved. Lord, by Thy favour Thou hast made my mountain to stand strong." We are in prosperity, and we say within ourselves that we shall never be moved. Our common temper is to calculate on our comforts continuing; we act just as if they were sure to do so; we give ourselves up to the things around us; our hearts are hardened, and we think not of God nor of His judgments.
II. The second state which the Psalmist describes will surely be ours; God will hide His face from us, and we shall be troubled. It is but too possible to lose our earthly good things, and yet gain no hope of heavenly things. It may be that our hearts will be hardened, that we shall have no desire to turn to God, though our earthly idols may be broken. Then God's face is indeed hidden, and for ever.
III. But the Psalmist goes on to say, "I cried to Thee, O Lord, and unto the Lord I made supplication." God had not so hidden His face from him as to refuse his prayers, or to make him unwilling to utter them. His troubles, whatever was their nature, were a wholesome chastening to him, and no more; they did but awaken him in time from his proud security. But the point to be observed is that we cannot reckon on troubles having this wholesome effect. The sorrow, indeed, is sure to come; but there is a sorrow which worketh death as well as a sorrow which leadeth to repentance.
T. Arnold, Sermons,vol. iii., p. 250.
References: Psalms 30:6-8. Archbishop Thomson, Lincoln's Inn Sermons,p. 310. Psalms 30:9-12. S. Baring-Gould, Village Preaching for a Year,1st series, vol. i., p. 289.