Isaiah 56:6-7

Also the strangers, that join themselves to the LORD, to minister unto him, and to love the name of the LORD, to be his servants, every one that keepeth the sabbath from profaning it, and holdeth fast by my covenant; even them will I bring to my holy mountain, and make them joyful in my house of prayer; their burnt offerings and their sacrifices shall be accepted upon mine altar: for mine house shall be called an house of prayer for all peoples.