Isaiah 56:6-7

And as for those from a strange country, who are joined to the Lord, to give worship to him and honour to his name, to be his servants, even everyone who keeps the Sabbath holy, and keeps his agreement with me: I will make them come to my holy mountain, and will give them joy in my house of prayer; I will take pleasure in the burned offerings which they make on my altar: for my house will be named a house of prayer for all peoples.