Charles H. Spurgeon on Psalms 27:3

Though an host should encamp against me, etc. He puts the case of the greatest danger that can be. Though an host should encompass me, my heart shall not fear: though war should rise against me, in this will I be confident. Here is great courage for the time to come. "Experience breeds hope and confidence." David was not so courageous a man of himself; but upon experience of God's former comfort and assistance, his faith brake as fire out of the smoke, or as the sun out of a cloud. Though I was in such and such perplexities, yet for the time to come, I have such confidence and experience of God's goodness, that I will not fear. He that seeth God by a spirit of faith in his greatness and power, he sees all other things below as nothing. Therefore, he saith here, he cares not for the time to come for any opposition; no, not of an army. "If God be with us, who can be against us?" Ro 8:31. He saw God in his power; and then, looking from God to the creature, alas! who was he? As Micah, when he had seen God sitting upon his throne; what was Ahab to him, when he had seen God once? So when the prophet David had seen God once, then "though an host should encamp against me, my heart shall not fear, "etc. Richard Sibbes.