Luke 9:28
"And it came to pass about an eight days after these sayings, he took Peter and John and James, and went up into a mountain to pray."
Cross References (ranked by relevance)
For my love they are my adversaries: but I give myself unto prayer.
And it came to pass in those days, that he went out into a mountain to pray, and continued all night in prayer to God.
And in the morning, rising up a great while before day, he went out, and departed into a solitary place, and there prayed.
And when he had sent them away, he departed into a mountain to pray.
And it came to pass, as he was alone praying, his disciples were with him: and he asked them, saying, Whom say the people that I am?
Who in the days of his flesh, when he had offered up prayers and supplications with strong crying and tears unto him that was able to save him from death, and was heard in that he feared;
And when he came into the house, he suffered no man to go in, save Peter, and James, and John, and the father and the mother of the maiden.
This is the third time I am coming to you. In the mouth of two or three witnesses shall every word be established.