Psalm 51/Notes/Textual.v. 20.539627
From Psalms: Layer by Layer
The MT reads the qal imperfect 2ms verb תִּבְנֶה with God as the implied subject and the walls as the direct object. The Greek, on the other hand, reads the niphal imperfect 3fp verb וְתִבָּנֶנָה, which makes the walls the subject of a passive construction meaning "and may the walls of Jerusalem be built."