'He spent the whole night, alone, in prayer to God', and at dawn Jesus chooses 12 disciples from among a large number of followers. He needed these men to be with him, while he taught the crowds, healed the sick and set the possessed free. Being with Jesus, watching him pray to his Father, being totally present to the crowds was the only way the Apostles could imbibe his Spirit into their own mission, when they too would be sent out to proclaim the 'good news' to the poor.
One of the first lessons the Apostles learn is spending time in prayer....being in communion with the Father, like Jesus, so they too like him would live radically 'poor' and 'available' for mission. They have been given a new identity, to be sent as 'witnesses'. They will stand in sharp contrast to those who oppose the Gospel. (6:11)
We are not given the "text" of Jesus' prayer all night on the mountain. He prayed - probably he didn't utter petition after petition to his Father. He was listening to his Father in the depths of his being. He was "seeing" the Father's plan, letting himself be illuminated by the one and light: his Father's will.
We cannot become Jesus' disciples unless we embrace as well the mission entrusted to us. In our daily surrender and death to self, we experience the death and resurrection of the Risen Lord. When Christ becomes the Centre of of our life we become true witnesses, in whom the Lord takes delight. (Ps. 149)
Father we lay our lives before You.