1)
What is the meaning of "Al Titnu Dami Lo"?
1.
Radak (6 citing Targum Yonasan, 7): Do not cease their mention from in front of Him, until He will fix and settle Yerushalayim [for] praise in the land. The matter is repeated to strengthen it.
2.
Malbim: Do not let Him be silent. Do not be silent until He founds and finishes the building, and until He makes Yerushalayim for praise and renown.
2)
Verse 6 said "Dami Lachem." Why does our verse say "Dami Lo"?
1.
Radak: One who speaks to his friend forces him to put his heart to all his words, without ceasing. When he ceases speaking, the silence is a break for the listener, just like for the speaker.
