Matthew Poole and continuators on Matthew 6:6

6 But thou, when thou prayest enter into thy closet, and when thou hast shut to thy door, pray to thy Father which is in secret, and thy Father which seeth in secret, shall reward thee openly.

By this, Publick Prayer is not Condemned, but secret Prayer is Established, and made every Christians Duty, and Christians are warned not to think that their Duty of Prayer is discharged by their going to places of Publick Worship and Praying there, but that which our Saviour here cautioneth us against, is Ostentation, by which Men may as much offend in their Closets as elsewhere, wherever we pray, we must take heed that our Ends be right, that the Glory of God be our Principal end, and yielding Obedience to his Command, and there is no better means in Order to this, than the right setting of God before our Eyes, as he that seeth in secret, and knoweth the most secret Designs, Scopes, and Intentions of our Hearts, and who if we thus perform our Duty, will reward us of his Free Grace and Mercy; not as Persons, who by our Prayers have merited any thing at his hand (for what Merit can there be in our Prayers, but as having shewed our Obedience to his Will, and in the fulfilling of those many Promises which he hath made to those that seek his Face, for the hearing of their Prayers.

Marginal references: 2 Kin. 4.33.