'It is Written' in the Bible

and that they should publish and proclaim through all their cities, and at Jerusalem, saying, Go forth to the mount, and fetch olive-branches, and wild olive-branches, and myrtle-branches, and palm-branches, and branches of thick trees, to make booths, as it is written.

And we cast the lots among the priests, the Levites, and the people, for the wood-offering, to bring it into the house of our God, according to our fathers' houses, at times appointed year by year, to burn upon the altar of Jehovah our God, as it is written in the law;

and the firstborn of our sons and of our cattle, as it is written in the law; and to bring the firstlings of our herds and of our flocks to the house of our God, to the priests that minister in the house of our God;