- People listen when we speak their language
- Seekers listen when we praise God and tell the wonders he has done
- What the apostles were to say when brought into court -- and no worrying in advance because the Spirit would help.
Jesus mentioned this to the apostles in advance. After the baptism of the Holy Spirit, we see the apostles actually on trial at times, and trusting that the words would come to proclaim what Jesus did.
- What the apostles said the first Pentecost
- What the apostles and other writers of Scripture would say, such as in their letters and in the gospels
All Scripture is God-breathed ...
- What the Christians would say to help and encourage each other
Some have the gift of encouragement or of teaching; some have words of wisdom or words of knowledge; the Spirit gives gifts including prophecy, tongues, or the interpretation of tongues. Jesus' people "are a letter from Christ, written with the Spirit of the Living God on tablets of the human heart" (2 Cor 3:3 selected/ellipses removed for easier reading)
- How the Christians would pray
The boldness to call God "Father" -- and the trust to see him as Father -- come from the Spirit. And when we lack words, we pray trusting that the Spirit communicates for us.