What does this Mizmor discuss?
Malbim: It discusses the praise of Yerushalayim. It depicts the entire nation as one body composed of different limbs. Yerushalayim is the city that connects it. It contains Ru'ach Chayim, intellectual Nefesh and Divine Nefesh.
Why does it say "l'David"?
Radak: David composed it. The other Shir ha'Ma'alos do not mention the author.
Why was he happy to hear "Beis Hashem Nelech"?
Rashi: People said, when will this elder (David) die, and his son Shlomo will reign and build the Beis ha'Mikdash, and we will ascend for the Regel. 1
Radak: Bnei Galus discuss ascending for the Regel amidst their great desire for Binyan Beis ha'Mikdash. They mention what their ancestors [while the Mikdash stood] said - each said "Samachti... Beis Hashem Nelech."
Malbim: Beis Hashem is the Kli that contains the body for the Shechinah and Divine Nefesh to rest in it. However, the city itself is like the heart and brain in a body, which prepare it to receive Nefesh Chayim and the intellectual Nefesh. The Simchah was because Hashem will dwell there.
David so much longed for Binyan Beis ha'Mikdash, for Hashem's honor, that he was happy to hear this. (PF)
