I've seen more statements by many of the Founding Fathers expressing similar abhorrance of slavery. I don't know the percentage of how many owned slaves; but not all did. I would like to know how many. Washington freed all of his in his will.
"It is much to be wished that slavery may be abolished. The honour
of the States, as well as justice and humanity, in my opinion,
loudly call upon them to emancipate these unhappy people.
To contend for our own liberty, and to deny that blessing to
others, involves an inconsistency not to be excused." --John Jay
"[Y]our late purchase of an estate in the colony of Cayenne, with
a view to emancipating the slaves on it, is a generous and noble
proof of your humanity. Would to God a like spirit would diffuse
itself generally into the minds of the people of this country;
but I despair of seeing it." --George Washington
George Washington: "there is not a man living who wishes more sincerely than I do, to see a plan adopted for the abolition of it."
John Adams: "Every measure of prudence, therefore, ought to be assumed for the eventual total extirpation of slavery from the United States…. I have, through my whole life, held the practice of slavery in …abhorrence."
Benjamin Franklin: "Slavery is …an atrocious debasement of human nature."
James Madison: "We have seen the mere distinction of colour made in the most enlightened period of time, a ground of the most oppressive dominion ever exercised by man over man."