Interestingly, the Disciples, particularly Peter, had already heard Jesus declare that His word is above all others. He says: “I say to you” nine times in Matthew 5 alone (18, 20, 22, 26, 28, 32, 34, 39, 44).

There are His other phrases, too, like "he who hears these sayings of mine and does them”.

Also: "Heaven and earth will pass away but My words will by no means pass away,” Luke 21'33. And, "No one comes to the Father except through Me,” John 14’6.

When the Lord said, “I say to you”, He meant it. After the Holy Spirit came Believers, being born of the Spirit, came alive to Jesus' words. Affectionately, He says: “My sheep hear my voice" (John 10’27). 

The Father's emphatic reminder to the Disciples to "Hear Him!" extends to all Believers, and more so to Saints who desire to rightly divide the word of truth (2 Timothy 2'15).