"Most assuredly I tell you, he who hears my word, and believes him who sent me, has eternal life, and doesn't come into judgment, but has passed out of death into life.
And He begins to talk to them now, emphasizing what He's saying with these words verily, verily. And the repetition of the word is for emphasis, it's, "Alright, now hear this." I mean, it's really calling their attention to what I'm about to say.