'Let your prayer be completely simple. For both the publican and the prodigal son were reconciled to God by a single phrase.'
'Do not be over-sophisticated in the words you use when praying, because the simple and unadorned lisping of children has often won the heart of their heavenly Father.'
'Do not attempt to talk much when you pray, lest your mind be distracted in searching for words. One word of the publican propitiated God, and one cry of faith saved the thief. Loquacity in prayer often distracts the mind and leads to phantasy, whereas brevity (Gr. monologia) makes for concentration.'
St. John of the Ladder (John Climacus) - 6th/7th cent