Rashi #1: This refers to 'ha'Omerah Elai" (10). The enemy says also, the day that you hope for to build your wall, it is far ? it will never come.

Rashi #2: The Navi informs Yisrael that there is a day to build the walls of their ruins. That day will distance and nullify from them the decrees of the Bavliyim and Persians.

Radak: This addresses the enemy. The day that you thought to build your wall with the spoils of Yisrael, when you will come to Eretz Yisrael with Gog and Magog, will distance your intent. It will be the opposite for you. You used to rule over Yisrael. (Then, Yisrael will rule over you!)

Radak citing Targum Yonasan: On that day, the congregation of Yisrael will be built [and the decree of the nations will cease].

Malbim: The day to build the pens for the scattered flock (Yisrael) will be gathered in them. This day is fixed. It is day ? its night is not with it. The previous days will be night (darkness of Galus), and not day. Its time is far, at the end of days.