Numbers 7:1-3

Now on the day that Moses had finished setting up the tabernacle, he anointed it and consecrated it with all its furnishings, and the altar and all its utensils; he anointed them and consecrated them also.

Then the leaders of Israel, the heads of their fathers’ households, made an offering (they were the leaders of the tribes; they were the supervisors over the numbered men).

When they brought their offering before the Lord, six covered carts and twelve oxen, a cart for every two of the leaders and an ox for each one, then they presented them in front of the tabernacle.