Charles H. Spurgeon on Psalms 61:3

For thou hast been a shelter for me. Observe how the psalmist rings the changes on, Thou hast, and I will, —Ps 61:3-6. Experience is the nurse of faith. From the past we gather arguments for present confidence. Many and many a time had the persecutions of Saul and the perils of battle imperilled David's life, and only by miracle had he escaped, yet was he still alive and unhurt; this he remembers, and he is full of hope. And a strong tower from the enemy. As in a fort impregnable, David had dwelt, because surrounded by omnipotence. Sweet is it beyond expression to remember the lovingkindnesses of the Lord in our former days, for he is unchangeable, and therefore will continue to guard us from all evil.