In the LDS scriptures, how many times does God actually speak? Like in D&C 49, God the Father and Jesus Christ seem to take turns speaking.
God the Father has spoken on very few occasions. When He does, it is to introduce His Son, Jesus Christ. We see this in the New Testament (when Jesus was baptized, and on the mount of transfiguration), the Book of Mormon (when Christ appears to the Nephites), and in the Pearl of Great Price (when the Father and Son appear to the boy Joseph). A variation on this theme is seen yet again where the Father testifies that Jesus is serving Him in very deed.
A few notable exceptions to this rule are when prophets or messengers speak with the Father directly and are sent with a message to believers. Most notably, the resurrected Jesus (who, in life, was the Father’s faithful messenger) delivered to the Nephites the words of the Father. Nephi also quoted the Father, but this remains more the exception than the rule.
At times Jesus (God the Son) will speak the words of God the Father in first person, as though He were God the Father. The First Presidency has referred to this as “divine investiture of authority”. They testify, “in all His dealings with the human family Jesus the Son has represented and yet represents Elohim His Father in power and authority” (The Father and the Son). Because of this, Jesus speaks of Himself in modern revelations in third person, using the titles that the Father placed upon Him. For instance, He is “mine Only Begotten“. Elder Talmage compares this authority to that of a legal agent:
“Jesus was the Father’s executive in pre-earth life, in mortality, and since his triumphant victory over death. Our Father in Heaven has allowed Jesus to speak to various prophets as if he were the Father. In the legal profession this is a well-understood practice referred to as the ‘power of attorney'” (“Articles of Faith”, Appendix 2, p. 470).
D&C 49 is no different in this respect than the other revelations Jesus has given. In the last verse, the Source identifies Himself, “I am Jesus Christ” (vs. 28). And yet, He still refers to Himself with the titles the Father has placed upon Him. He is “mine Only Begotten Son“, “the Son of Man“, and refers to His return as “the great day of the Lord“.
Ultimately, it doesn’t make a difference whether it is the Father’s words or the Son’s words spoken in the revelation. Jesus testified that He does the works of the Father and says the words of the Father. Though they are two distinct persons, they are truly One.