For this cause therefore the Jews sought all the more to kill him, because he not only broke the Sabbath, but also called God his own Father, making himself equal with God.
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.