Deuteronomy 23:6

You shall not seek their peace nor their prosperity all your days forever.

Ezra 9:12

Now therefore give not your daughters unto their sons, neither take their daughters unto your sons, nor seek their peace or their wealth forever: that you may be strong, and eat the good of the land, and leave it for an inheritance to your children forever.

2 Samuel 8:2

And he struck Moab, and measured them with a line, casting them down to the ground; even with two lines measured he the ones to put to death, and with one full line the ones to keep alive. And so the Moabites became David's servants, and brought gifts.

2 Samuel 12:31

And he brought forth the people that were therein, and put them to work with saws, and with picks of iron, and with axes of iron, and made them toil at the brick kilns: and thus did he unto all the cities of the children of Ammon. So David and all the people returned unto Jerusalem.

Nehemiah 13:23-25

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

Treasury of Scripture Knowledge

Summary

Thou shalt not seek their peace nor their prosperity all thy days for ever.

Bible References

Thou shalt

2 Samuel 8:2
And he struck Moab, and measured them with a line, casting them down to the ground; even with two lines measured he the ones to put to death, and with one full line the ones to keep alive. And so the Moabites became David's servants, and brought gifts.
2 Samuel 12:31
And he brought forth the people that were therein, and put them to work with saws, and with picks of iron, and with axes of iron, and made them toil at the brick kilns: and thus did he unto all the cities of the children of Ammon. So David and all the people returned unto Jerusalem.
Ezra 9:12
Now therefore give not your daughters unto their sons, neither take their daughters unto your sons, nor seek their peace or their wealth forever: that you may be strong, and eat the good of the land, and leave it for an inheritance to your children forever.
Nehemiah 13:23
In those days also saw I Jews that had married wives of Ashdod, of Ammon, and of Moab: