Psalms 18:18 - Coke's Commentary on the Holy Bible

They prevented me in the day of my calamity— i.e. "came on me suddenly, unawares, when I was unprovided and helpless; and must have destroyed me, had not God upheld and supported me when I was in danger of perishing." God was to the Psalmist for a staff, to support him. What a staff is to one who is ready to fall, the means of recovering and preserving him, that was God to David in the time of his extremity.