This is a subsidiary post of Scripture.
(I have many notes to add to this post.)
Consider how often the expressions “the word of the Lord” and “the word of God” are found in the Bible.
MORE SUBTLE CLAIMS
The very word “promise” when associated with “God” implies that God has spoken. It is the prophets who recorded these promises (Romans 1:2). Therefore, even verses that don’t explicitly go into the detail that God made His promises through prophets are implying that such records are records of what He has said (e.g. Acts 13:32-33).