And when thou prayest ... - Hypocrites manifested the same spirit about prayer as almsgiving; it was done in public places. The word “synagogues,” here, clearly means, not the place of worship of that name, but places where many were accustomed to assemble - near the markets or courts, where they could be seen of many. Our Lord evidently could not mean to condemn prayers in the synagogues. It might be said that he condemned ostentatious prayer there, while they neglected secret prayer; but this does not appear to be his design. The Jews were much in the habit of praying in public places. At certain times of the day they always offered their prayers. Wherever they were, they suspended their employment and paid their devotions. This is also practiced now everywhere by Muslims, and in many places by Roman Catholics. It seems, also, that they sought publicity, and regarded it as proof of great piety.
Related Commentaries of Matthew 6:5
Matthew 6:5
5 And when thou prayest, thou shalt not be as the hypocrites are: for they love to pray standing in the synagogues and in the corners of the streets, that they may be seen of men. Verily I say unto you, They have their reward.