President Washington’s 1789 proclamation of “a day of public thanksgiving and prayer…” (for the entire proclamation go here.)

Now therefore I do recommend and assign Thursday the 26th day of
November next to be devoted by the People of these States to the
service of that great and glorious Being, who is the beneficent Author
of all the good that was, that is, or that will be– That we may then
all unite in rendering unto him our sincere and humble thanks–for his
kind care and protection of the People of this Country previous to
their becoming a Nation–for the signal and manifold mercies, and the
favorable interpositions of his Providence which we experienced in the
course and conclusion of the late war–for the great degree of
tranquility, union, and plenty, which we have since enjoyed–for the
peaceable and rational manner, in which we have been enabled to
establish constitutions of government for our safety and happiness, and
particularly the national One now lately instituted–for the civil and
religious liberty with which we are blessed; and the means we have of
acquiring and diffusing useful knowledge; and in general for all the
great and various favors which he hath been pleased to confer upon us.