Using an unusual transsexual image, Isaiah promises that Israel will “suck the milk of nations and suck the breast of kings” (Isaiah 60:16). Gentile kings will take the place of Moses, the “nursing father” of Israel (cf. Numbers 11:12).
And not just Moses: Most of the references to milk in the Old Testament come in the phrase “a land flowing with milk and honey.” Once the land provided the milk, but in future Israel will receive her milk not from the land but from the provision of kings of the nations.
That sets up Israel for the coming of the Christ, who is the land in person and who appears to John in Revelation 1 with “breasts” by which He nurses His people.