Isaiah 56:6-8

6“Also the foreigners who join themselves to the Lord, To minister to Him, and to love the name of the Lord, To be His servants, everyone who keeps the Sabbath without profaning it And holds fast to My covenant [by conscientious obedience];

7All these I will bring to My holy mountain And make them joyful in My house of prayer. Their burnt offerings and their sacrifices will be accepted on My altar; For My house will be called a house of prayer for all the peoples.”

8The Lord God, who gathers the dispersed of Israel, declares: “I will gather yet others to them (Israel), to those [already] gathered.”