1)
Why does it say that Yir'ei Hashem will return to David?
1.
Rashi (from Sanhedrin 107a): The Sanhedrin separated from him when he became a Metzora due to that sin. Even if [Bas Sheva] was divorced, he put his eyes on her; "anyone who touches her 1 will not be cleansed" (Mishlei 6:29; Sifri Devarim 345).
2.
Radak: When they see that Zedim are ashamed, they will return to give to me good tidings, and strengthen me in my Emunah.
3.
Malbim: Even though Zedim will not return to see the light of life - "Kol Ba'eha Lo Yeshuvun" (Mishlei 2:19) - Yir'ei Hashem will return to me. The Pikudim are a remembrance of the testimony; they will return to Emunah and guarding Pikudim 2 .
