Nehemiah 13:3

13:3 When they heard the law, they removed from Israel all who were of mixed ancestry.

Nehemiah 13:30

13:30 So I purified them of everything foreign, and I assigned specific duties to the priests and the Levites.

Ezra 9:2

9:2 Indeed, they have taken some of their daughters as wives for themselves and for their sons, so that the holy race has become intermingled with the local residents. Worse still, the leaders and the officials have been at the forefront of all of this!”

Ezra 10:11

10:11 Now give praise to the Lord God of your fathers, and do his will. Separate yourselves from the local residents and from these foreign wives.”