John Gill Commentary 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 prosperity for ever; that ye may be strong, and eat the good of the land, and leave it for an inheritance to your children for ever." — Ezra 9:12 (ASV)

Now therefore give not your daughters to their sons, nor
take their daughters to your sons
That is, in marriage, see (Deuteronomy 7:3), where the prohibition is expressed in the same language:

nor seek their peace or their wealth for ever;
that is, as long as they continue in their idolatries and impurities, see (Deuteronomy 23:6),

that you may be strong, and eat the good of the land, and leave it
for an inheritance to your children for ever;
that they might be strengthened and established in the land into which they were brought, and enjoy all the good things it produced, and leave their children in the possession of it, to hold at least until the Messiah came, see (Isaiah 1:19).