1 Peter 1:16

Because it is written, Be ye holy; for I am holy; literally, according to the best manuscripts, ye shall be holy—future for imperative. The words occur five times in the Book of Leviticus. God had called the Israelites to be his peculiar people, a kingdom of priests and a holy nation ( Exodus 19:5 , Exodus 19:6 ). He has called us Christians to be "a chosen generation, a royal priesthood, a holy nation, a peculiar people" ( 1 Peter 2:9 ). He is holy, awful in holiness; in his sight "the heavens are not clean." We who are his must strive to be holy, separated from all that is impure, consecrated to his service.