Numbers 36:6

This [is] the word that Yahweh commanded the daughters of Zelophehad, saying, '{Let them marry} {whomever they like}; only {they must marry} from within the clan of the tribe of their father.

Genesis 24:57-58

And they said, "Let us call the girl and ask {her opinion}."

Numbers 36:12

{They married} those from the sons of Manasseh son of Joseph, and their inheritance {remained} among the tribe of the clan of their ancestors.

Genesis 24:3

that I may make you swear by Yahweh, the God of heaven and the God of earth, that you will not take a wife for my son from the daughters of the Canaanites in whose midst I am dwelling,

2 Corinthians 6:14

Do not become unevenly yoked with unbelievers, for what participation [is there between] righteousness and lawlessness? Or what fellowship [does] light [have] with darkness?

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
{They married} those from the sons of Manasseh son of Joseph, and their inheritance {remained} among the tribe of the clan of their ancestors.
Genesis 24:3
that I may make you swear by Yahweh, the God of heaven and the God of earth, that you will not take a wife for my son from the daughters of the Canaanites in whose midst I am dwelling,
2 Corinthians 6:14
Do not become unevenly yoked with unbelievers, for what participation [is there between] righteousness and lawlessness? Or what fellowship [does] light [have] with darkness?