Commenting on Isaiah 56:3-8, which talks about the inclusion of foreigners and eunuchs among God’s people, foreigners and eunuchs, that is, who keep the Sabbath and the covenant, Walter Brueggemann notes that:

the community welcomes members of any race or nation, any gender or social condition, so long as that person is defined by justice, mercy, and compassion, and not competition, achievement, production, or acquisition. (Sabbath as Resistance: Saying No to a Culture of Now)

Quite so! Brueggemann is also right, it seems to me, to suggest that this ‘stance of generous inclusiveness’ is a direct contradiction of the Mosaic rules in Deuteronomy 23:1-8. Isaiah’s words are an example of prophetic critique of Israel’s ancient traditions, the kind of critique that Jesus was to continue some centuries later.