Doctrine & Covenants 20:17, 19, 28

17 – By these things we know that there is a God in heaven, who is infinite and eternal, from everlasting to everlasting the same unchangeable God, the framer of heaven and earth, and all things which are in them;

19 – And gave unto them commandments that they should love and serve him, the only living and true God, and that he should be the only being whom they should worship.

28 – Which Father, Son, and Holy Ghost are one God, infinite and eternal, without end. Amen.