Charles H. Spurgeon on Psalms 91:5

The true remedy against tormenting fear is faith in God; for many terrible things may befall men when they are most secure, like unto those which befall men in the night: but for any harm which may befall the believer this way, the Lord here willeth him to be nothing afraid: Thou shalt not be afraid for the terror by night. Many sadder accidents may befall men when they are most watching and upon their guard, but the Lord willeth the believer to be confident that he shall not be harmed this way: Thou shalt not be afraid for the arrow that flieth by day. Many evils are men subject unto, which come upon them men cannot tell how, but from such evils the Lord assures the believer he shall have no harm: Thou shalt not be afraid of the pestilence which walketh in darkness. Men are subject to many evils which come upon them openly, and not unawares, such as are calamities from enemies and oppressors; the Lord willeth the believer to be confident that he shall not be harmed this way: Thou shalt not be afraid for the destruction that wasteth at noonday. David Dickson.