Luke says Jesus "continued all night in prayer to God" (6:12). What did he pray about?

Luke doesn't say. He tells where Jesus went and for how long: "In these days, he went out to the mountain to pray, and he continued all night in prayer to God" (6:12). And he tells what came next: "When it was day, he called his disciples, and from them he chose twelve, whom he also named apostles" (6:13). Luke gives no words of the prayer, and these notes don't supply them, or say that the choosing was what he prayed about. Luke tells of Jesus praying at other times too, among them "he withdrew himself into the desert and prayed" (5:16) and "As he was praying alone, the disciples were near him" (9:18). Favor's Luke 5 asks why he withdrew to pray in 5:16, and finds no reason given there either.