Do not fail those who weep, but mourn with those who mourn: Good News Translation‘s translation is a fine model. Contemporary English Version is also helpful:

• Go to see them [the mourners]
and weep as they mourn.

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.