Matthew 6:7
And when you pray use not vain repetitions, as the gentiles do; for they think they shall be heard for their much speaking.
Matthew 23:13
But woe to you scribes and Pharisees, hypocrites! For you shut up the kingdom of heaven before men; for you enter not into it, neither do you suffer those entering to go in.
Luke 13:25-28
When the householder has risen and shut the door, and you stand without and knock at the door, saying, Lord, open to us, and he will answer and say to you, I know you not whence you are,
1 Timothy 2:8
I wish also that men should pray everywhere, lifting up holy hands, without wrath and disputations;