Neither shall he profane his seed by mixing it with forbidden kinds, whereby the children would be disparaged, and rendered unfit for their priestly function. Do sanctify him, i.e. have separated him from all other sorts of men for my especial and immediate service, and therefore will not have that race corrupted.
Related Commentaries of Leviticus 21:15
Leviticus 21:15
15 Neither shall he profane his seed among his people: for I the LORD do sanctify him.