Jesus trusted the Bible that would be written in what would be His future. How do we know? We just see hints about this in the teaching of Jesus. But we can see it.
Jesus promised that the Holy Spirit would assist His followers remember His words.
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 have said to you.
John 14:26 (ESV)
This is a big deal. Jesus is saying that before the NT was written, the Holy Spirit was working to make sure that the followers of Jesus would verbally communicate truths that could be trusted. And then the Holy Spirit would work to make sure that what they later wrote could be trusted.
This explains that what was written by the first followers of Jesus was seen by the early church as having the same authority as the OT.
When the Spirit of truth comes, He will guide you into all the truth… and He will declare to you the things that are to come.
John 16:13-14 (ESV)
The work of the Holy Spirit was to guide the followers of Jesus so that their memory of the words and the work of Jesus was completely accurate.
Later in John 17 , Jesus prays for His first followers and their impact on future followers – on people like us. And notice how He prays.
I [pray] for those who will believe in Me through their word…
John 17:20 (ESV)
He’s praying so that what was said and written in the future could be trusted. These are hints from the lips of Jesus that the words and the writings from His followers that were yet to come could be trusted. The first followers of Jesus were simply passing along what they had received from Jesus.
Jesus trusted the Bible past, present, and future.