He kept the law of the Most High, and was taken into covenant with him: For the Most High, see 4.10. A covenant is an agreement (see 17.12). Was taken into covenant with him refers to Gen 17.1-14. Good News Translation “made a covenant with him” is seriously misleading. It suggests that Abraham made the covenant with God, when actually God made the covenant with Abraham. New Revised Standard Version has “entered into a covenant with him,” which could pass for a literal translation of the Hebrew. The Greek actually says “came to be in a covenant with him.” For this whole line we could say “He kept the law of the Most High, and had an agreement with him.”

He established the covenant in his flesh: This refers to circumcision as a sign of the covenant (see Gen 17.10-14). He refers to Abraham. For this line New Jerusalem Bible is clearer with “He confirmed the covenant in his own flesh,” or we may say “He confirmed this agreement with a sign [or, mark] in his body.” By being circumcised, Abraham affirmed or ratified the agreement with God; he signified his submission to it, indicating that he would abide by it.

And when he was tested he was found faithful: The reference here is probably to Gen 22. Was found is equivalent to “showed himself to be” or “proved to be.” The last two lines of this verse could be rendered “He bore a sign of that agreement on his own body, and whenever the Lord tested his loyalty [to the agreement], he was faithful.”

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on Sirach. (UBS Helps for Translators). New York: UBS, 2008. For this and other handbooks for translators see here.