Article II, Section 1, Clause 8

further provides, That the president shall, previous to his entering upon the duties of his office, take the following oath or affirmation : I do solemnly swear (or affirm) that I will faithfully execute the office of president of the United States, and will, to the best of my ability, preserve, protect, and defend the constitution of the United States. Thus we see that instead of the president's being vested with all the powers of a monarch, as has been asserted, that he is under the immediate controul of the…

Cites "Section i, of article II" (OCR "i" for "1") and reproduces the President's oath from this clause verbatim.

Before he enters on the execution of his office, he ſhall take the following oath or affirmation: I do ſolemnly ſwear (or affirm) that I will faithfully execute the office of Preſiden of the United States, and will, to the beſt of my ability, preſerve, protect,…

The paragraph prints Article II, Section 1, Clause 8 of the Constitution as signed; the quoted words are the same as the clause's (apart from capitals and the long s), though the pamphlet's punctuation differs in places.

Yet the framers of this new constitution did not even think it necessary that the president should believe that there is a God, although they require an oath of him.

The paragraph names the oath required of the president, which is prescribed in Article II, Section 1, clause 8.

…of the office, shall each “solemnly swear or affirm, that he will faithfully execute the office of President of the United States, and will, to the best of his ability, preserve, protect, and defend, the Constitution of the United States.”

The passage quotes the oath of the President in quotation marks; the oath in the clause reads "my Ability" where the passage has "his ability".

As to the President of the United States, his oath is specified in the Constitution; and as the Vice President, in the event of the resignation or death of the President, is to exercise the same office, the only doubt I have ever had…

The paragraph names the President's oath as specified in the Constitution, which is Article II, Section 1, Clause 8.