: The prologue of the book of Ben Sira is the only biblical text that gives us a reflection on the act of translating. This article has two objectives : 1) to better understand what Ben Sira's grandson says about the translation of his grandfather's book ; 2) to compare his conception of translation with those found in other Judean and Alexandrian texts relating to the translation of the Hebrew Bible into Greek, to highlight the singular character of the remarks of Ben Sira's grandson.