Midrasch zu Tehillim 102:14

(Fol. 87) It is written (Is. 62, 6) I have set watchmen upon thy walls, O Jerusalem. They shall never be silent, day nor night. Ye that make the Lord's remembrances, take ye no rest. What did they say? Said Raba b. R. Shila (Ps. 102, 14) Thou wilt arise, and have compassion upon Zion; for it is time to be gracious unto her, for the appointed time is come. R. Nachman b. Isaac said: (Ib. 147, 2) The Lord does build up Jerusalem, He gathereth together the dispersed of Israel. And what did they say before [the destruction of the Temple]? Said Raba b. R. Shila: (Ib. 132, 13) For the Lord hath chosen Zion; He hath desired it for His habitation.