When did David compose this Mizmor?
Radak: It was when he built the Mizbe'ach in the granary of Aravnah ha'Yevusi, according to Gad ha'Navi. He offered Olos and Shelamim on it and called to Hashem, and Hashem answered him with fire on the Mizbe'ach - "Zeh Hu Beis Hashem Elokim v'Zeh Mizbe'ach l'Olah l'Yisrael" (Divrei ha'Yamim I, 22:1). Until that day, the place of the Beis ha'Mikdash was not known 1 . Nasan ha'Navi already told David that he will not build the Beis ha'Mikdash, rather, his son Shlomo will.
Malbim: It was for when they entered the Aron into the Kodesh ha'Kodoshim. It is divided into three parts. The first is when they carried the Aron on the road.
This is unlike Zevachim 54b, which says that David and Shmuel were not in Nayos (Shmuel I, 19:18). Rather, they determined where will be the Noy (beauty) of the world, i.e. the Beis ha'Mikdash. (PF)
What is "Kol Unoso"?
Rashi: His Nefesh's affliction, that he toiled to find a place for You.
Radak: I stole (denied) sleep from my eyes, from my many thoughts about it. I vowed and swore not to rest until I build it, and I did not find contentment in my house, since Beis Hashem was not built.
Malbim: David was Moser Nefesh for bringing the Aron, like it says in Shmuel II, Perek 7.
What does he request Hashem to do?
Radak: Remember that I put all my strength and ability to prepare Binyan ha'Bayis, and I was answered in the chosen place. Since I did not merit to build it, let my intent be considered like deed.
