We need a frame of reference when God wants to speak through us. Jesus tells us that when we are brought before governors and kings for His sake we will be given what to say by the Holy Spirit.
19“But when they hand you over, do not worry about how or what you are to say; for it will be given you in that hour what you are to say. 20“For it is not you who speak, but it is the Spirit of your Father who speaks in you. (Matthew 10:19-20 NASB95. See also Mark 13:11 and Luke 12:11)
How will we know what to say unless we have His Words filling our hearts? I suppose He could do it like a supernatural ventriloquist, but that’s not the way He usually does things. Except maybe with donkeys (Numbers 22).
26“But the Helper, the Holy Spirit, whom the Father will send in My name, He will teach you all things, and bring to your remembrance all that I said to you. (John 14:26 NASB95)
We aren’t dummies (I’ll refrain from the puns) so it’s much more likely that He will bring to our remembrance what has been laid up inside of us for just that occasion. If we read His Words and do them on a regular basis, the Spirit has a full storehouse of living oracles from which to draw.
‘Whole Bible Christianity’ chapter 9 section on Read and Strive to do