Instructions on baptism for members of The Church of Jesus Christ of Latter-day Saints in D&C 20:72-74.
Section 20:72-74, Doctrine and Covenants, The Church of Jesus Christ of Latter-day Saints
72 Baptism is to be administered in the following manner unto all those who repent—
73 The person who is called of God and has authority from Jesus Christ to baptize, shall go down into the water with the person who has presented himself or herself for baptism, and shall say, calling him or her by name: Having been commissioned of Jesus Christ, I baptize you in the name of the Father, and of the Son, and of the Holy Ghost. Amen.
74 Then shall he immerse him or her in the water, and come forth again out of the water.