Charles H. Spurgeon on Psalms 91:5

Not that we are always actually delivered out of every particular danger or grievance, but because all will turn (such is our confidence in God) to our greater good; and the more we suffer the greater shall our reward and our glory be. To the same purpose is the expression of Isaiah: "When thou passest through the waters, I will be with thee; and through the rivers, they shall not overflow thee; when thou walkest through the fire, thou shalt not be burned; neither shall the flame kindle upon thee." Isa 43:2. So also Hab 3:17-18, "Although the fig tree shall not blossom, "&c.; and Job 5:19-20, etc. And therefore here is no ground, if the words be rightly understood, for any man absolutely to presume or conclude that he shall actually be delivered out of any particular danger; much less upon such a presumption wilfully to run into dangers. If such figures, the ornament of all language; such rhetorical, emphatic amplifications be allowed to human writers, and well enough understood in ordinary language; why not to holy writers as well, who had to do with men, as well as others; whose end also was to use such expressions as might affect and move? That human writers have said as much of the security of good and godly men, I shall need to go no further than Horace his Ode, Integer vitae scelerisque purus, &c. Most dangerous then and erroneous is the inference of some men, yea, of some expositors, here, upon these words of the psalmist, that no godly man can suffer by the plague, or pestilence: nor is old Lactantius his assertion much sounder, Non potest ergo fieri, quin hominem justum inter descrimina tempestatum, &c., that no just man can perish by war, or by tempest. (Instit. 1. v, c. 18). Most interpreters conclude here, that the godly are preserved in time of public calamities; which, in a right sense, may be true; but withal they should have added, that all godly men are not exempted at such times; to prevent rash judgments. Westminster Assembly's Annotations.