Read Matthew 6:5-8
Did you know that the word hypocrite in Greek actually means an actor, stage player or pretender? In other words, it is someone who is pretending to be what they are not. In the matter of prayer Jesus said these types of people, "Love to pray standing in the synagogues and on the corners of the streets, that they may be seen by men" (Matthew 6:5). In other words, they made a show of the fact they were praying to God so that people would think they were righteous. But Jesus said "When you pray, go into your room, and when you have shut your door, pray to your Father who is in the secret place; and your Father who sees in secret will reward you openly" (Matthew 6:6). Does this mean that all public prayer is wrong? Not at all. For it is clear from scripture that corporate prayer was practised (Acts 12:12). But to understand what was really going on we need to look at the culture of the day behind Jesus' statements.
When the Temple stood there were regular times of prayer, and scripture confirms this (Psalms 55:17; Daniel. 6:10; Acts 3:1). However, when the time of prayer occurred pious Jews would stop what they were doing, no matter where they were, and make a great show of the fact that they were praying. It is clear from Matthew 6:5 that if they hadn't made it into the Temple for the prayer time they would go to great lengths to show those around them that they were indeed still praying. Proving Jesus' point that they were hypocrites who cared more about what people thought of them, than actually praying to God. Hence, Jesus' admonishment to pray in secret.
Jesus also said, "Do not use vain repetitions as the heathen do. For they think that they will be heard for their many words" (Matthew 6:7). This is another area that must be looked at from Jesus' 2nd century viewpoint. Idol worship was rampant during these times and idol worshippers often chanted for hours the same words or phrases, over and over again to appease the gods. Jesus' words seem to indicate that some Jews were of the mind that maybe that's how they should pray to God as well - by chanting. In 1 Kings 18:26 Baal worshippers chanted from mid-evening to morning. The multitude in the theatre at Ephesus shouted for two hours “Great is Artemis of the Ephesians” (Acts 19:34). But Jesus said, "Do not be like them" (Matthew 6:8).
Yet, today we find many popular Christian leaders encouraging chanting as a means to centre ourselves to become more focused on God. They are ignoring Jesus' warnings against such things. Popular Christian author and pastor Tony Campolo says, "I say His name over and over again, for as long as fifteen minutes, until I find my soul suspended in what the ancient Celtic Christians called a ‘thin place’—a state where the boundary between heaven and earth, divine and human, dissolves. You could say that I use the name of Jesus as my koan” (Campolo, Mystical Encounters for Christians). FYI - A ‘koan’ is used in Zen Buddhism as an aid to meditation and a means of gaining spiritual awakening. This is something very similar to what the pagans did during Jesus time and so we should avoid it.
So how do we apply Jesus' principles to our prayer times?
Three Steps to Appropriate Prayer Times