Why does it say "Od Evnech v'Nivneis"?
Rashi: You had two buildings (Batei Mikdash) built through people; therefore they were destroyed. I Myself will build the third. It will be permanent; you will always be adorned.
Radak: This is a metaphor. The scattered congregation [of Yisrael] is like a destroyed building; its rocks and wood were scattered. When it is built, they are gathered.
Malbim: This is building the kingship and the Bayis.
Why does it say "Besulas Yisrael"?
Radak: You will still be like a virgin; you did not have Bi'ah with masters other than Me.
Why will you adorn yourselves with drums?
Radak: Amidst the great good, you will go out and celebrate with drums and dances. The drums will be like adornments for you. Malbim - this is like the women went out after Miryam with drums and dances due to the miracle of Keri'as Yam Suf.
