Isaiah
Isaiah 56:6ESV·traditional attribution

“And the foreigners who join themselves to the LORD, to minister to him, to love the name of the LORD, and to be his servants, everyone who keeps the Sabbath and does not profane it, and holds fast my covenant—

Matthew Henry Presbyterian @wholebiblehenry

The prophet is here, in God's name, encouraging those that were hearty in joining themselves to God and yet laboured under great discouragements. 1. Some were discouraged because they were not of the seed of Abraham. They had joined themselves to the Lord, and bound their souls with a bond to be his for ever (this is the root and life of religion, to break...

Commenting on Isaiah 56:3-8

John Gill Reformed Baptist @doctorgill

Also the sons of the stranger that join themselves to the Lord,.... Having answered the objection and removed the discouragement of the eunuch, he now returns to the sons of the stranger, who also join themselves to the Lord, as the eunuch had done; see Isa 56:4 and who do this, to serve him, and to love the name of the Lord, to be his...

Jamieson-Fausset-Brown Reformed @jfbcommentary

join . . . Lord-- (Jer 50:6). Conditions of admission to the privileges of adoption.