To where did he return?
Rashi: To inside Chatzer ha'Penimis.
Radak: To Pesach ha'Heichal.
Malbim: To the eastern opening of Ezras Yisrael.
What is "Pnei ha'Bayis"?
Malbim: It is the east (the Bayis faces east).
What is "Kesef ha'Bayis"?
Radak: Kesef is what is in back of the gate, or outside of it. Perhaps it exuded under the threshold of the southern Pishpesh (of Sha'ar ha'Heichal), for no one entered there.
Where does the water flow?
Rashi (1-2): It flows from under the right (southern) Kesef ha'Bayis, under the threshold, in the middle of the east, and goes on a diagonal to the right, and leaves the Azarah to the south of the Mizbe'ach, and goes outside the city. In Yuma (77b), it says that the spring that exudes from Kodesh ha'Kodoshim is initially [thin] like antennae of grasshoppers. Once it reaches Pesach ha'Heichal, it becomes like a warp thread. Once it reaches Pesach ha'Ulam, it becomes like a woof thread 1 . Once it reaches Pesach ha'Azarah, it becomes like the mouth of a small flask 2 .
Malbim: This water of knowledge begins from intellect that is Ne'etzal from Olam ha'Atzeilus; Kodesh ha'Kodoshim hints to it. It is like grasshopper antennae, for we understand a mere needle's (width) of that great light. Pesach ha'Heichal hints to Olam ha'Kisei; more will be understood. Pesach ha'Ulam hints to the world of angels ? the knowledge will grow, and leave the Azarah to the physical world of Ofanim. There is it is like a flask; people understand and investigate Chachmah of Shamayim and the lowly world.
Radak: A Mishnah (Midos 2:6) teaches that Sha'ar ha'Mayim, via it they enter a flask of water for Nisuch ha'Mayim during Sukos.
What is the significance of south of the Mizbe'ach?
Malbim (5): This Kadosh water of Da'as, Torah and Emunah come from under the threshold of the southern Kesef ha'Bayis, south of the Mizbe'ach. It is not from the north, which is special for Shechitah of Kodshei Kodoshim which are mostly to atone for sin, e.g. Chatas and Asham. Also Olah atones for [sinful] thoughts 1 , and a Lav Nitak l'Aseh (the Torah gave an Aseh to fix transgression of the Lav). The water of Da'as will not come from there ? people will not know Hashem amidst fear of punishment, rather, to the right of the Mizbe'ach, where they offer Korbanos of Ratzon ? Shelamim and Todah, which show Avodas Hashem amidst recognizing his good, Chesed and Emes.
Malbim mentioned also Pesha (intentional sin). Some Ashamos are even for Mezid, and Olah can be for Mezid. (PF)
