Numbers 18:26
“Talk to the Levites and explain to them, ‘When you receive from the Israelites the tithe that I have given you as your compensation, you must return part of it as an offering to the Lord: a tithe of the tithe.“Talk to the Levites and explain to them, ‘When you receive from the Israelites the tithe that I have given you as your compensation, you must return part of it as an offering to the Lord: a tithe of the tithe.