The Epistle to the Hebrews, the authorship of which has been long debated, urges the Hebrew Christian community not to fall back into Judaism.

Hebrews 9

9:19 For when Moses had spoken every precept to all the people according to the law, he took the blood of calves and of goats, with water, and scarlet wool, and hyssop, and sprinkled both the book, and all the people,