In 1784, to Robert R. Livingston, Benjamin Franklin wrote:

I am now entering on my 78th year....If I live to see this peace concluded, I shall beg leave to remind the Congress of their promise, then to dismiss me. I shall be happy to sing with old Simeon, "Now lettest thou thy servant depart in peace, for mine eyes have seen thy salvation."

In a letter dated April 17, 1787, Benjamin Franklin stated:

Only a virtuous people are capable of freedom. As nations become corrupt and vicious, they have more need of masters.

On Thursday, June 28, 1787, Benjamin Franklin delivered a speech to the Constitutional Convention, which was embroiled in a debate over how each state was to be represented in the new government. The hostile feelings, created by the smaller states being pitted against the larger states, was so bitter that some delegates actually left the Convention.
Benjamin Franklin, being the President (Governor) of Pennsylvania, hosted the rest of the 55 delegates attending the Convention. Being the senior member of the convention at 81 years of age, he commanded the respect of all present, and, as recorded in James Madison's detailed records, rose to speak in this moment of crisis:

Mr. President:
The small progress we have made after 4 or 5 weeks close attendance & continual reasonings with each other - our different sentiments on almost every question, several of the last producing as many noes as ayes, is methinks a melancholy proof of the imperfection of the Human Understanding.
We indeed seem to feel our own want of political wisdom, since we have been running about in search of it. We have gone back to ancient history for models of Government, and examined the different forms of those Republics which, having been formed with the seeds of their own dissolution, now no longer exist. And we have viewed Modern States all
round Europe, but find none of their Constitutions suitable to our circumstances.
In this situation of this Assembly, groping as it were in the dark to find political truth, and scarce able to distinguish it when presented to us, how has it happened, Sir, that we have not hitherto once thought of humbly applying to the Father of lights to illuminate our understanding?
In the beginning of the Contest with G. Britain, when we were sensible of danger, we had daily prayer in this room for Divine protection. - Our prayers, Sir, were heard, & they were graciously answered. All of us who were engaged in the struggle must have observed frequent instances of a Superintending Providence in our favor.
To that kind Providence we owe this happy opportunity of consulting in peace on the means of establishing our future national felicity. And have we now forgotten that powerful Friend? or do we imagine we no longer need His assistance?
I have lived, Sir, a long time, and the longer I live, the more convincing proofs I see of this truth - that God Governs in the affairs of men. And if a sparrow cannot fall to the ground without His notice, is it probable that an empire can rise without His aid?
We have been assured, Sir, in the Sacred Writings, that "except the Lord build the House, they labor in vain that build it." I firmly believe this; and I also believe that without his concurring aid we shall succeed in this political building no better than the Builders of Babel: We shall be divided by our partial local interests; our projects will be confounded, and we ourselves shall become a reproach and bye word down to future ages.
And what is worse, mankind may hereafter from this unfortunate instance, despair of establishing Governments by Human wisdom and leave it to chance, war and conquest.
I therefore beg leave to move - that henceforth prayers imploring the assistance of Heaven, and its blessing on our deliberations, be held in this Assembly every morning before we proceed to business, and that one or more of the clergy of this city be requested to officiate in that service.

The response of the convention to Dr. Benjamin Franklin's speech was reported by General Jonathan Dayton, the delegate from New Jersey and later Speaker of the House of Representatives, to William Steele:

The Doctor sat down; and never did I behold a countenance at once so dignified and delighted as was that of Washington at the close of the address; nor were the members of the convention generally less affected. The words of the venerable Franklin fell upon our ears with a weight and authority, even greater that we may suppose an oracle to have had in a Roman senate!

Following Franklin's historical address, Roger Sherman of Connecticut seconded his motion. Edmund Jennings Randolph of Virginia moved:

That a sermon be preached at the request of the convention on the 4th of July, the anniversary of Independence;
& thenceforward prayers be used in ye Convention every morning. [Dr. Franklin seconded this motion.]

The clergy of the city responded to this request and effected a profound change in the convention, as noted by General Jonathan Dayton when they reconvened, July 2, 1787:

We assembled again; and...every unfriendly feeling had been expelled, and a spirit of conciliation had been
cultivated.