Jesus said His sheep hear His voice, know Him, and follow Him, and that He gives them eternal life which no one can snatch away; those who do not belong to His flock are those who will not listen to Him.
The sermon presses this further with the Father’s word at the Transfiguration to simply ‘listen to Him,’ and with Jesus’ warning that how we hear determines what more will be given. It closes with Revelation’s blessing on those who hear and keep His words, since Christ, who is coming again, calls His people to stay alert and obedient to His voice.