Those who fear the Lord will prepare their hearts: This means that people who honor the Lord will be constantly at his service, always ready to learn, hear what God has to say, and stand ready to carry out his will. Good News Translation “Those who fear the Lord are always ready to serve him” is a good model.

And will humble themselves before him means “and will humble themselves in his presence.” God-fearing people act with due humility when dealing with holy matters. So we may say “and humble themselves as they worship him.”

Good News Translation adds “and say” to the end of this verse, because verse 18 is a rough quotation of a saying of David given in 2 Sam 24.14.

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.