Numbers 11:18

(18) Sanctify yourselves against to-morrow.—(Comp. Exodus 19:10.) The Israelites were required to sanctify themselves by purification for the more immediate manifestation of the Divine presence, although their request was a sinful one, and was granted in judgment as well as—or even more than—in mercy. Comp. Psalms 106:15 : “And he gave them their request; but sent leanness into their soul.”