Isaiah56chapter 56

Two groups are named because two groups had been shut out by name. The Law of Moses barred the emasculated man from the assembly of the LORD, and it restricted certain foreign peoples. Those were not abstract categories. Empires routinely castrated captured boys for palace and harem service, so a Judean family taken to Babylon could easily produce a son who was a court official and permanently excluded from his own people's worship.

What the eunuch is offered answers the exact thing he lost. He says, I am a dry tree — a man whose family line ends with him, in a culture where the name carried on through sons was your only afterlife on earth. God offers him a place and a name in my house and within my walls, better than of sons and of daughters, an everlasting name that shall not be cut off.

The Sabbath is named repeatedly here for a practical reason. In exile there was no temple, no altar, and no land, so the two things that could still be kept anywhere were circumcision and the Sabbath. Keeping the Sabbath became the visible line between remaining a Jew and dissolving into the empire.

The last section turns on watchmen and sheepdogs, and the language is rough. Israel's watchmen are blind, they are all ignorant, they are all dumb dogs that cannot bark, lying down and loving to slumber. A shepherd's dog earns its food by barking at what comes out of the dark; a dog that sleeps through it is worse than useless. Then the shepherds themselves: they cannot understand, they all look to their own way, every one for his own gain.