“I don't know what this so-called pure gospel is. Was the preaching of John the Baptist pure? He did not say only, "Repent, for the kingdom of heaven is at hand!" (Matthew 3:2). He also "rebuked [Herod]… for all the evils which Herod had done" (Luke 3:19). He was beheaded because he didn't confine himself to abstract teaching. Jesus did not preach only the "pure" Sermon on the Mount, but also what some actual church leaders would have called a negative sermon: "Woe to you, scribes and Pharisees, hypocrites!… Serpents, brood of vipers!" (Matthew 23:27,33). It is for such "impure" preaching that He was crucified. The Pharisees would not have bothered about the Sermon on the Mount.”

Vol. I, Ch. 11: Of the Times of the Birth and Passion of Christ
Observations upon the Prophecies of Daniel, and the Apocalypse of St. John (1733)

"Where Art Thou?", p. 40
Startling Questions (1853)

The Doctrine of Repentance (1668)

On the Sermon on the Mount, as translated by William Findlay (1888), Book I, Ch. 1 http://www.newadvent.org/fathers/16011.htm
Context: If any one will piously and soberly consider the sermon which our Lord Jesus spoke on the mount, as we read it in the Gospel according to Matthew, I think that he will find in it, so far as regards the highest morals, a perfect standard of the Christian life: and this we do not rashly venture to promise, but gather it from the very words of the Lord Himself. For the sermon itself is brought to a close in such a way, that it is clear there are in it all the precepts which go to mould the life. … He has sufficiently indicated, as I think, that these sayings which He uttered on the mount so perfectly guide the life of those who may be willing to live according to them, that they may justly be compared to one building upon a rock.

As quoted in The Life of Florence Nightingale (1913) by Edward Tyas Cook, p. 392

Drafts on the history of the Church (Section 3). Yahuda Ms. 15.3, National Library of Israel, Jerusalem, Israel. 2006 Online Version at Newton Project http://www.newtonproject.sussex.ac.uk/view/texts/normalized/THEM00220

But I could see a hint of fear in his eyes.
Space (1912)

Book I : The Beginnings, Ch. V : The Baptism Of The Penguins
Penguin Island (1908)
Context: Thinking that what he saw were men living under the natural law, and that the Lord had sent him to teach them the Divine law, he preached the gospel to them.
Mounted on a lofty stone in the midst of the wild circus:
"Inhabitants of this island," said he, "although you be of small stature, you look less like a band of fishermen and mariners than like the senate of a judicious republic. By your gravity, your silence, your tranquil deportment, you form on this wild rock an assembly comparable to the Conscript Fathers at Rome deliberating in the temple of Victory, or rather, to the philosophers of Athens disputing on the benches of the Areopagus. Doubtless you possess neither their science nor their genius, but perhaps in the sight of God you are their superiors. I believe that you are simple and good. As I went round your island I saw no image of murder, no sign of carnage, no enemies' heads or scalps hung from a lofty pole or nailed to the doors of your villages. You appear to me to have no arts and not to work in metals. But your hearts are pure and your hands are innocent, and the truth will easily enter into your souls."
Now what he had taken for men of small stature but of grave bearing were penguins whom the spring had gathered together, and who were ranged in couples on the natural steps of the rock, erect in the majesty of their large white bellies. From moment to moment they moved their winglets like arms, and uttered peaceful cries. They did not fear men, for they did not know them, and had never received any harm from them; and there was in the monk a certain gentleness that reassured the most timid animals and that pleased these penguins extremely.