Charles Ellicott Commentary Matthew 6:5

"And when ye pray, ye shall not be as the hypocrites: for they love to stand and pray in the synagogues and in the corners of the streets, that they may be seen of men. Verily I say unto you, They have received their reward." — Matthew 6:5 (ASV)

Standing in the synagogues — The Jewish custom, more or less prevalent throughout the East and retained for a time at certain seasons in the Christian Church, was to pray standing with outstretched, uplifted hands. There was nothing in the posture itself that made it an act of ostentatious devotion, nor would it have been ostentatious to join in the common prayer of the congregation in the synagogue. What our Lord’s words point to is the custom of going into the synagogue for private devotion (as, for example, in the parable of the Pharisee and the publican) and doing so to attract notice. The worshipper would stand apart as if absorbed in prayer, while secretly glancing around to watch the impression he might be making on others who were watching.

In the corners of the streets — This does not use the same word as in Matthew 6:3, but instead refers to the broad, open places of the city. There, too, the Pharisees could be seen reciting their appointed prayers—likely the well-known eighteen acts of devotion prescribed for devout Israelites—with the tallith, or prayer veil, over their heads.