Daniel Webster delivered a speech in Boston on August 2, 1826 as a celebration of the lives of John Adams and Thomas Jefferson, who had both died on July 4, 1826, 50 years after the Declaration of Independence was signed. The complete speech can be found in his book Daniel Webster for Young Americans: The Greatest Speeches of the Defender of the Constitution. This excerpt from the speech presents a supposed speech of John Adams in favor of the Declaration. I transcribed it in Anniversary Gregg.
Attachment: john-adams-in-favor-of-independence.pdf