Why does it say "Ki v'Har Kodshi"?
Radak: Now I do not want your gifts 1 . When Yisrael will be in Har Kodshi, when they return from Galus, "Sham Ertzem" (refer to 20:40:3:1).
Malbim: This is because now you serve idolatry. There will be three differences. (a) Now they do not serve Me totally - they serve also idolatry. Then they will serve only Me. (b) Now, only some serve Me - then, all will serve Me. (c) Now they serve in Chutz la'Aretz, which is not prepared for Kedushah. Then, they will serve Me in the land.
Why does it say "b'Har Merom Yisrael"?
Refer to 17:23:1:1.
What is the meaning of "Sham Ertzem"?
Radak: There I will be pleased with them via their Korbanos and good deeds. Malbim - therefore, I will desire their Terumos.
Why does it say "Sham Ya'avduni Kol Beis Yisrael Kulo ba'Aretz"?
Radak: Since it said above "u'Varosi Mikem ha'Moredim veha'Posh'im Bi" (38), here it says "Kol Beis Yisrael Kulo"; "ba'Aretz" teaches those who will merit to return to the land. Not one of them will be missing; all will serve Me there. Kulo doubles the matter to strengthen it. This is like "v'Chol Tzarayich Kulam ba'Shevi Yelechu" (30:16). It is strengthened to teach that even though in the war of Gog and Magog, not one of them will die, even though they will be in affliction. Yonason translates "ba'Aretz" as 'in a living land.'
What will Hashem seek there?
Radak: There I will want them to offer to Me, as if I seek their Korbanos. When their deeds are good, their Korbanos and Terumos are pleasant to Me.
What are "[Reishis] Mas'oseichem"?
Rashi: This is like Mish'aroseichem (your doughs), an expression of food, like "She'erah Kesusah v'Onasah Lo Yigra" (Shemos 21:10).
Malbim: They are Bechor, Chalah and Bikurim.
What are "b'Chol Kodsheichem"?
Malbim: They are other Kodshim, especially since Terumos and Ma'aseros in Chutz la'Aretz are only mid'Rabanan.
