Matthew 6:5

To pray standing] Standing was the usual Jewish attitude in prayer, as kneeling is with us. In prayer a Jew usually (1) stood, (2) turned towards Jerusalem, (3) covered his head, (4) fixed his eyes downwards. The ancient Church prayed standing on Sundays and festivals, but kneeling on fast-days, and the Eastern Church still observes this rule.

In the synagogues and in the corners of the streets] During the synagogue services those who wished to be thought devout did not follow the public prayers, but said private self-righteous prayers of their own, loud enough to be heard and to attract the attention of the congregation. In the streets the same people would sometimes stand for three hours at a time in the attitude of prayer. The prayers of the phylacteries (see on Matthew 23:5) were required to be said at a fixed time with great parade and ceremony. When the time came, the workman put down his tools, the rider descended from his ass, the teacher suspended his lecture, to say them. The ostentatious were careful to be overtaken by the prayer-hour in a public place, and to remain longer praying than any one else.