‘And it came about in these days, that he went out into the mountain to pray; and he continued all night in prayer to God.'
We should note that prior to choosing the twelve Jesus went into the mountain to pray and continued all night with God. This is the only place where we are informed that He prayed all night. How far He had already made His selection in His mind we do not know, but He would not move without God's confirmation. That He should spend the whole night brings out how important He considered the choices to be. Each candidate would be sifted before God before acceptance.