What is the meaning of "Gam Mehem Ekach la'Kohanim la'Leviyim"?
Rashi citing Shocher Tov 87:6: From those who bring them 1 , and from the Yisraelim brought, I will take Kohanim and Leviyim. I know the Kohanim and Leviyim among them; I will select them from among them, and they will serve in front of Me.
Radak: Even from those who were sunk (assimilated) amidst Goyim on distant islands, to the point that they were not remembered and did not ascend from Galus with their Jewish brothers. It is possible that they deviated from the creed somewhat. Even so, Hashem will take from the Kohanim and Leviyim among them to serve in front of Him. Leviyim serve via singing with harps and lyres.
Radak citing his father: From [the Goyim who bring Yisrael] I will take for the needs of the Kohanim, to chop wood and draw water. "V'Lo Yihyeh Kena'ani Od b'Veis Hashem" (Zecharyah 14:21) - i.e. the Giv'onim, who used to chop wood and draw water [will not be in Beis Hashem]; from the greatest of the Goyim will be servants of the Kohanim.
Malbim: Also those who served idolatry, and they were from Kohanim or Leviyim of proper lineage, they did not lose their privilege. Since this was b'Ones, they will be Kohanim and Leviyim.
Radak citing the Midrash: They were sold to be slaves, and forgot that they were Jewish, and amidst Ones, 'became' Goyim. (Hashem will clarify the Kohanim, Leviyim and Yisraelim among them.) Targum Yonasan is like this.
Why does it say "Amar Hashem"?
Rashi citing Shocher Tov 87:6: It says "ha'Nistaros la'Shem Elokeinu" (Devarim 29:28).
