Is this passage plagiarized? I think so, because only the author's name is given and not the page number in the in-text citation.

"...fathers brought forth on this continent a new nation, conceived in liberty and dedicated to the proposition that all men are created equal." (Lincoln)

3 answers

No. Further citation is not needed for anything as well known as these words from Lincoln's Gettysburg Address.
What about this one? It isn't as well known.

"No doubt the feat was easy to Mr. Utterson; for he was undemonstrative at the best, and even his friendship seemed to be founded in a similar catholicity of good-nature." (Stevenson)
"No doubt the feat was easy to Mr. Utterson; for he was undemonstrative at the best, and even his friendship seemed to be founded in a similar catholicity of good-nature." (Stevenson)

not plagiarized because you have the name Stevenson and you have quotations to signal that someone else said it. It may not be a fully correct citation since it doesn't have page number but it should be okay.