Charles H. Spurgeon on Psalms 121:8

The Lord shall preserve. The word "shamar" imports a most tender preservation; from it comes "shemuroth", signifying the eyelids, because they are the keepers of the eye, as the Lord is called in the verse preceding —shomer Ishrael, "the keeper of Israel". If the lids of the eye open, it is to let the eye see; if they close, it is to let it lest, at least to defend it; all their motion is for the good of the eye. O, what a comfort is here! The Lord calls his Church "the apple of his eye": "he that toucheth you, touches the apple of mine eye". The Church is the apple of God's eye, and the Lord is the covering of it. O, how well are they kept whom "the keeper of Israel" keepeth! The Lord was a buckler to Abraham, none of his enemies could harm him; for his buckler covered him thoroughly. The Lord was a hedge unto Job; Satan himself confessed he could not get through it, howsoever many a time he assayed it, to have done evil unto Job. . . . But seeing this same promise of preservation was made before (for from the third verse to the end of the Psalm, six sundry times, is the word of keeping or preserving repeated), why is it now made over again? Not without cause; for this doubling and redoubling serves, first, for a remedy of our ignorance. Men, if they be in any good estate, are ready to "sacrifice to their own net, "or "to cause their mouth to kiss their own hand, "as if their own hand had helped them: thus to impute their "deliverance" to their "calf, "and therefore often is this resounded, "The Lord, " "The Lord." Is thy estate advanced? The Lord hath done it. Hast thou been preserved from desperate dangers? Look up to the Lord, thy help is from on high, and to him let the praise be returned. Secondly, it is for a remedy of our natural diffidence: the word of the Lord in itself is as sure when it is spoken, as when it is sworn; as sure spoken once, as when it is oftener repeated; yet is not the Lord content to speak only, but to swear also; nor to speak once, but often, one and the selfsame thing. The reason is showed us by the apostle, that hereby he may "declare to the heirs of promise the stability of his counsel." Heb 6:1 Ge 21:32. As Joseph spake of Pharaoh his vision, "It was doubled, because the thing is established by God, and God hasteth to perform it"; so is it with every word of the Lord, when it is repeated; it is because it is established, and God hastens to perform it. —From a Sermon by Bishop Couper, entitled "His Majesties Coming in," 1623.