This verse refers to the prohibition against intermarriage of Jews and Gentiles in Deut 7.3.

Therefore (literally “And now”) is a discourse marker that indicates the next development in the prophets’ statement, which is the prohibition against intermarriage. It is very emphatic. Revised English Bible says “Now therefore.”

Do not give your daughters in marriage to their sons, and do not take their daughters for your sons: This statement is a parallelism that forbids both the marriage of Israelite women into a foreign society and the bringing of foreign women into Israel in marriage. Even though the Revised Standard Version rendering is unnatural English, the expressions “giving your daughters” and “taking their daughters” reflect the patriarchal view of society that was prevalent in Israel at the time. This viewpoint is lost in Good News Bible‘s restructuring of the prohibition with the English verb “intermarry.” It is preferable to retain the reflection of Jewish marriage practice in the translation, if the vocabulary of the receptor language allows it.

Good News Bible, continuing in indirect speech, renders this verse as “They [the prophets] told us that we should never intermarry with these people.” It is an acceptable model, although much is condensed with the word “intermarry,” as noted above. Some translators may find following Revised Standard Version more closely is easier. Another possible model that uses direct speech is:

• So do not let your sons and daughters marry their sons and daughters.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on 1-2 Esdras. (UBS Helps for Translators). Miami: UBS, 2019. For this and other handbooks for translators see here.