Mark 9
In Mark 9, Jesus said that some standing around Him would not taste death until they saw the kingdom of God arrive with power. The very next thing it tells about is Jesus taking three disciples up on a mountain where they saw Him transfigured into His kingdom glory with Moses and Elijah. Maybe those three disciples are the ones He was talking about earlier.
Jesus met with Moses and Elijah on earth. That means Moses and Elijah witnessed Jesus on earth in His earthly ministry. Could that mean that Moses and Elijah are the two witnesses in Revelation 11:3-12? Those witnesses both have the same powers that Moses and Elijah demonstrated during their earthly ministries. I think there's a strong connection here.
Another strong connection is between the Feast of Tabernacles and Peter wanting to build tents for Jesus, Moses, and Elijah. This feast is associated with the second coming of Christ, and Peter's desire to build tents for them must mean that He understood it as a fulfillment of a Messianic prophesy. Otherwise Peter's request just seems odd and out of place.
The disciples certainly understood something about the Messianic prophecies, though, because they started asking the right questions - "why do the scribes say Elijah must come first?" To which Jesus answered that Elijah already came.
Then there's a teaching about the power of faith and prayer. The disciples could not cast out a demon that possessed a boy since a young age. Jesus rebuked their unbelief. Then the father of the boy demonstrated his own unbelief with the question "if you can," and Jesus admonished him saying that all things are possible to those who believe. The father's reply is one of my favorite - "I do believe; help my unbelief." That's a statement I myself make often.
Jesus cast out the spirit, but He added an additional part to His command - "never enter him again." Casting out demons is a two step process. First get the demon out, then invite the Holy Spirit in, otherwise the demon might return.
And Jesus says the power to cast out demons comes from prayer. Some manuscripts add fasting, and a lot of people make a big deal about including fasting, but don't overlook the primary importance of prayer. Whether you fast or not, prayer is the primary source of God's power working through you.
Then Jesus told them again that He must die, and the disciples did not understand Him. In fact, their minds were on the complete opposite. They were arguing about who was going to have the highest positions in Jesus kingdom - assuming that He was going to overthrow Rome and restore Israel to being a sovereign nation. Their mindset was the complete opposite of Jesus's, even to the point where they were jealous that someone else was demonstrating the power they received from Jesus. They wanted to stop another person from casting out demons in Jesus name because that person was not part of their group - sounds a little like the Pharisees, doesn't it.
Who cares what you're doing or why, you're threatening my position so stop it!
Jesus had to explain to them that no level of service done in Jesus name is to be despised, but rewarded instead - even giving someone a cup of water.
Jesus then said that if anyone opposes or hinders someone doing things in His name their fate would be worse than they could imagine. He's trying to make a point, not prescribe a course of action, when He says it would be better to cut your hand off if it causes you to sin. We are to be ruthless when it comes to rooting sin out of our own lives, but we are not to hinder others when they are trying to do the will of God.
Be salty. Have the flavor of Jesus about you.