Teaching – before the Church had a New Testament.
Acts 18.11 Paul stayed at Corinth for 18 months “teaching the word of God”.
The early church had an understanding God’s word was not just a “written down in the past thing” but could also be a “spoken in present thing”. And in the Old Testament it was often a spoken thing which was written down afterwards.
The early church had the view that when a person was speaking words inspired by the Spirit of Jesus it was the word of God the Spirit. – irrespective of who was speaking it.Jesus gave instructions through the HS in Acts 1.2; Christians speak by the Spirit in Acts 2. 4;
This feature of Christianity is what Jesus meant in John 14. 26 when he said the Spirit of Jesus would teach us. When we, by the Spirit, teach what the HS teaches us this too is the word of God. And this is the way it was before the church had it’s New Testament.