Numbers 36:6

this is the thing which Jehovah hath commanded concerning the daughters of Zelophehad, saying, To those good in their eyes let them be for wives; only, to a family of the tribe of their fathers let them be for wives;

Genesis 24:57-58

and they say, 'Let us call for the young person, and ask at her mouth;'

Numbers 36:12

to men of the families of the sons of Manasseh, son of Joseph, they have been for wives, and their inheritance is with the tribe of the family of their father.

Genesis 24:3

and I cause thee to swear by Jehovah, God of the heavens, and God of the earth, that thou dost not take a wife for my son from the daughters of the Canaanite, in the midst of whom I am dwelling;

2 Corinthians 6:14

Become not yoked with others -- unbelievers, for what partaking is there to righteousness and lawlessness?

Treasury of Scripture Knowledge

Summary

This is the thing which the LORD doth command concerning the daughters of Zelophehad, saying, Let them marry to whom they think best; only to the family of the tribe of their father shall they marry.

Bible References

Only to the family

Numbers 36:12
to men of the families of the sons of Manasseh, son of Joseph, they have been for wives, and their inheritance is with the tribe of the family of their father.
Genesis 24:3
and I cause thee to swear by Jehovah, God of the heavens, and God of the earth, that thou dost not take a wife for my son from the daughters of the Canaanite, in the midst of whom I am dwelling;
2 Corinthians 6:14
Become not yoked with others -- unbelievers, for what partaking is there to righteousness and lawlessness?