en_tn_condensed/isa/05/17.md

the sheep will feed as in their own pasture

Yahweh will destroy the city of Jerusalem, which was called a "vineyard" in Isaiah 5:1. It will become good for nothing except for sheep to eat grass there.

in the ruins, lambs will graze as foreigners

That is, the lambs will graze there. The land will be worthless for any other use.