The Levites could only undertake their duties (Numbers 3; Numbers 4) after the formal exchange of the Levites for the first-…

Instead of such as open every womb, even instead of the firstborn of all the children of Israel, have I taken them unto me.

For…

For all the firstborn of the children of Israel [are] mine ,
[both] men and beasts
No…

Here we have directions for the solemn ordination of the Levites. All Israel must know that they did not take this honor to themselves, but were ca…