Two verses I often see misused amongst Christian mystics (and I am speaking as a Christian mystic here) are "Be still, and know that I am God" from Pslam 46 and "the kingdom of God is within you" from Luke 17.
Again, context is the issue.
Read holistically, Psalm 46 is a psalm about finding refuge in a time of trouble, most likely war. In verses immediately proceeding the one in question it is said,
"Come and see the works of the LORD, the desolations he has brought on the earth. He makes wars cease to the ends of the earth; he breaks the bow and shatters the spear, he burns the shields with fire."
This is the psalm of the terrified soldier not the psalm of the tranquil monk. That's not to say the instruction can't be transferred to other contexts, but let's face it, it's not the firmest verse to build a contemplative prayer ministry on.
Read holistically, Luke 17:21 is better translated as "the kingdom of God is among you" or "in your midst" than "within you". Most bible translations acknowledge this as an alternate reading, but most scholars insist it's the alternate reading that's the more contextual one. Consider the verses proceeding the saying:
Once, having been asked by the Pharisees when the kingdom of God would come, Jesus replied, "The kingdom of God does not come with your careful observation, nor will people say, 'Here it is,' or 'There it is,' because the kingdom of God is [in your midst]."
Note it is the pharisees Jesus is speaking to here, not the disciples. Jesus is the king they do not recognize, ushering in a kingdom they actively oppose. It would be ironic in the extreme for Jesus to identify the Pharisees as bearers of the kingdom. More likely Jesus is making an oblique reference to himself and his activity. So again, if you are looking for a verse that expresses an experience of unity with God this in not the best one.