Consider:
I. In what sense David could say, "Thou hast been a shelter to me," and then that he was fully justified in concluding, "I will abide in Thy tabernacle for ever; I will trust in the covert of Thy wings." The argument before us is not precisely that which we could venture in all cases to employ with our fellow-men. Man is changeable, and the goodwill which he once showed to us may no longer exist, but may have been transferred to others, who will, in their turn, be forced to give way to new objects. But the case is wholly changed when the benefactor is God. Here there is no limitation to the power, for "the eyes of all wait upon Him, and He satisfieth the desire of every living thing." Neither can there be change in the will, for "with Him is no variableness, neither shadow of turning." There is not a single answer received to prayer which may not serve as a promise that if we ask again, again we shall obtain.
II. Consider how past mercies may be used as motives to the expecting fresh at God's hands. Let mercies be remembered as well as enjoyed, and they must be as lights in our dark days and as shields in our perilous. If I find a believer in Christ cast down because exposed to vehement temptation, I would tell that man that he does wrong in looking thus on the future; he is bound to look also on the past. Can he remember no former temptation from which he came out a conqueror, no seasons of danger when God showed Himself a very present help? And what then has he to do but to gird up the loins of his mind, and to "pray without ceasing"? In one way or another, keep the past before you if you would look the future calmly in the face. Treasure your experience. Double life by living over again every case of trial in which God has shown Himself your Friend. Let experience do its part, and faith shall hardly be languid. When you pray, "Lead me to the rock that is higher than I," call earnestly to mind what cause you have to say, "Thou hast been a shelter for me, and a strong tower from the enemy," and your language shall soon be that of confidence and exultation: "I will abide in Thy tabernacle for ever; I will trust in the covert of Thy wings."
H. Melvill, Penny Pulpit,No. 2151 (see also Voices of the Year,vol. i., p. 97).
References: Psalms 61:3. M. G. Pearse, Sermons to Children,p. 131; Bishop Woodford, Sermons on Subjects from the Old Testament,p. 129. Psalms 61:7. Spurgeon, Evening by Evening,p. 43.Psalms 62:1; Psalms 62:2. A. Maclaren, Expository Sermons and Outlines on the Old Testament,p. 229.