Isaiah 56:2-6

Blessed is the man that doeth this, and the son of man that holdeth it fast; that keepeth the sabbath from profaning it, and keepeth his hand from doing any evil. Neither let the foreigner, that hath joined himself to Jehovah, speak, saying, Jehovah will surely separate me from his people; neither let the eunuch say, Behold, I am a dry tree. For thus saith Jehovah of the eunuchs that keep my sabbaths, and choose the things that please me, and hold fast my covenant: Unto them will I give in my house and within my walls a memorial and a name better than of sons and of daughters; I will give them an everlasting name, that shall not be cut off. Also the foreigners that join themselves to Jehovah, to minister unto him, and to love the name of Jehovah, to be his servants, every one that keepeth the sabbath from profaning it, and holdeth fast my covenant