Charles Ellicott Commentary Isaiah 48:21

"And they thirsted not when he led them through the deserts; he caused the waters to flow out of the rock for them; he clave the rock also, and the waters gushed out." — Isaiah 48:21 (ASV)

He caused the waters to flow ... —A dead, prosaic literalism makes people wonder that there is no record of such wonders on the return from Babylon. A truer insight recognizes that the “water out of the rock” is, as ever, the symbol of spiritual refreshment (Isaiah 41:17–19; Isaiah 43:19–20; John 4:10).