Pseudo-Chrysostom
Catena Aurea · Matthäusevangelium 6
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. But thou, when thou prayest, enter into thy closet, and when thou hast shut thy door, pray to thy Father which is in secret; and thy Father which seeth in secret shall reward thee openly.
But I suppose that it is not the place that the Lord here refers to, but the motive of him that prays; for it is praiseworthy to pray in the congregation of the faithful, as it is said, In your Churches bless ye God. (Ps. 68:26.) Whoever then so prays as to be seen of men does not look to God but to man, and so far as his purpose is concerned he prays in the synagogue. But he, whose mind in prayer is wholly fixed on God, though he pray in the synagogue, yet seems to pray with himself in secret. In the corners of the streets, namely, that they may seem to be praying retiredly; and thus earn a twofold praise, both that they pray, and that they pray in retirement.