Though God be not changed by it (prayer) in Himself, yet the real change that is made by it on ourselves, doth infer a change in God by mere relation or extrinsical denomination; He being, according to the tenor of His own covenant, engaged to punish the unbelieving, prayerless, and disobedient, and to pardon them that are faithfully desirous and obedient. So that in prayer, faith and fervency are so far from being useless, that they as much prevail for the thing desired by qualifying our selves for it, as if indeed they moved the mind of God to a real change; even as he that is in a boat, and by his hook layeth hold of the bank, doth as truly by his labor get nearer the bank, as if he drew the bank to him. (Richard Baxter)
God can pick sense out of a confused prayer. (Richard Sibbs)
Set prayers are prescript forms of our own or others composing; such are lawful for any, and needful for some.
Lawful for any. Otherwise God would not have appointed the priests a form of blessing the people. Nor would the Saviour have set His prayer, which is both a prayer in itself, and a pattern or platform of prayer.
Needful for some. Namely, for such who as yet have not attained to pray extempore by the Spirit. But as little children are so ambitious of going alone, that they scorn to take the guidance of a form or bench to direct them, but will venture by themselves ... so many confess their weakness, in denying to confess it, who, refusing to be beholden to a set form of prayer, prefer to say nonsense, rather than nothing, in their extempore expressions. More modesty, and no less piety, it had been for such men to have prayed longer with set forms that they might pray better without them. (Thomas Fuller)
Is it lawful to pray in a set form of words? Nothing but very great ignorance can make you really doubt it. Hath God anywhere forbid it? You will say that it is enough that He hath not commanded it. I answer, That in general He hath commanded it you you all be done to edification; but He hath given to you no particular command or prohibition. No more hath He commanded you to pray in English, French, or Latin; nor to sing psalms in this tune or that; nor after this or that version or translation. (Richard Baxter)
Hath it not the show of error to say that no man may use any set prayer, seeing there be many set prayer, and psalms, and blessings in the Holy Scripture, which were used in the same form? (Henry Smith)
Overvalue not therefore the manner of your own worship, and over vilify not other men's of a different mode. (Richard Baxter)