In Chapter Eight ~ The Disciples on pages 104-105, Jimmy tells John about a number of New Testament passages alluding to Jesus teaching his disciples something private. Here are some of the passages he's referring to: Matthew 11:1, 13:10 and 17; Mark 4:10, 4:33, 8:27, and 11:20-24; Luke 8:10, 10:23, and 11; John 3:22 and 6:3.
Thomas Moore's Writing In the Sand: Jesus, Spirituality, and the Soul of the Gospels sheds the most spiritual and realistic light on the life and teachings of Jesus. I also highly recommend his translations of the gospels, with commentary: Matthew, Mark, Luke, John.