A common mistake we run into today is taking a promise made to the apostles, commandeering it as a promise to us, and then imagining that the promise applies equally to us. For example, when Jesus promised the apostles that the Holy Spirit would "guide you into all truth" (John 16:13), people think that they can appropriate that promise to themselves and just imagine that the Spirit is guiding them. The context is showing a special conversation Jesus is having with his twelve apostles, those Jesus was equipping to be the eyewitnesses with power to testify accurately of Him for all people of all time to come. Jesus did not promise everyone that the Spirit would guide them into all truth. The Spirit came upon the apostles and equipped them. Our job is to read the testimony the Spirit gave through the apostles (Ephesians 3:3-5).
By listening to the Spirit's written testimony given through the apostles we are listening to the Spirit. They got direct guidance, and we get indirect guidance. They were promised direct guidance and then wrote it down. We read the testimony and believe what the Spirit says. We hear what the Spirit says through scriptures (Revelation 2:7; II Timothy 3:16-17). The apostles were promised the direct guidance that produced for us the words we read in the scriptures. We do not get the same direct guidance. We cannot produce a written record that carries the same authority as the written records of the Bible.