"Now if Jesus prays and does so not in vain, since He gets what He asks for in prayer when He might not have done so apart from prayer, which of us would neglect to pray? Mark says that 'in the morning, a great while before day, He rose and went out to a lonely place, and there He prayed' (Mark 1.35). And Luke says, 'He was praying in a certain place, and when He ceased, one of His disciples said to Him' (Luke 11.1) and elsewhere, 'And all night he continued in prayer to God' (Luke 6.12). And John records His prayer, saying, 'When Jesus had spoken these words, He lifted up His eyes to heaven and said, 'Father, the hour has come; glorify your son that the son may glorify you' (John 17.1). The same evangelist writes that the Lord said that He knew 'you hear me always' (John 11.42), and this shows that the one who prays 'always' is 'always' heard."
Origen, On Prayer