Nehemiah 13:23

In those days I also saw Jews who had married women from Ashdod, Ammon, and Moab.

Nehemiah 10:30

and that we will not give our daughters [as wives] to the peoples of the land or take their daughters for our sons.

Ezra 9:1-2

When these things were completed, the officials came to me and said, “The people of Israel and the priests and Levites have not separated themselves from the peoples of the lands, but have committed the repulsive acts of the Canaanites, Hittites, Perizzites, Jebusites, Ammonites, Moabites, Egyptians, and Amorites.

Ezra 10:10

Then Ezra the priest stood up and said to them, “You have been unfaithful [to God] and have married foreign (pagan) women, adding to the guilt of Israel.

Nehemiah 13:1

On that day they read aloud from the book of Moses so that the people could hear [its words], and in it was found written that no Ammonite or Moabite could ever enter the assembly of God,

1 Samuel 5:1

Then the Philistines took the ark of God, and they brought it from Ebenezer to Ashdod.

Ezra 9:11-12

which You have commanded by Your servants the prophets, saying, ‘The land which you are entering to possess is a defiled land with the uncleanness of the peoples of the lands, through their repulsive acts which have filled it from one end to the other along with their impurity.

Ezra 10:44

All these had married foreign women, and some of them had wives by whom they had children.

Nehemiah 4:7

But when Sanballat, Tobiah, the Arabs, the Ammonites, and the Ashdodites heard that the repair of the walls of Jerusalem went on, and that the breaches were being closed, they were very angry.

2 Corinthians 6:14

Do not be unequally bound together with unbelievers [do not make mismatched alliances with them, inconsistent with your faith]. For what partnership can righteousness have with lawlessness? Or what fellowship can light have with darkness?

Treasury of Scripture Knowledge

Summary

In those days also saw I Jews that had married wives of Ashdod, of Ammon, and of Moab:

Bible References

Married

Nehemiah 10:30
and that we will not give our daughters [as wives] to the peoples of the land or take their daughters for our sons.
Ezra 9:2
For they have taken some of their daughters as wives for themselves and for their sons, so that the holy race has intermingled with the peoples of the lands. Indeed, the officials and chief men have been foremost in this unfaithful act and direct violation [of God’s will].”
Ezra 10:10
Then Ezra the priest stood up and said to them, “You have been unfaithful [to God] and have married foreign (pagan) women, adding to the guilt of Israel.
2 Corinthians 6:14
Do not be unequally bound together with unbelievers [do not make mismatched alliances with them, inconsistent with your faith]. For what partnership can righteousness have with lawlessness? Or what fellowship can light have with darkness?

Ammon

Nehemiah 13:1
On that day they read aloud from the book of Moses so that the people could hear [its words], and in it was found written that no Ammonite or Moabite could ever enter the assembly of God,

General references

Exodus 34:16
and you might take some of his daughters for your sons, and his daughters would play the prostitute with their gods and cause your sons also to play the prostitute (commit apostasy) with their gods [that is, abandon the true God for man-made idols].
Deuteronomy 7:3
You shall not intermarry with them; you shall not give your daughter to his son, nor shall you take his daughter for your son;
Judges 3:6
and they took their daughters for themselves as wives and gave their own daughters to their sons, and served their [pagan] gods.