“Morality after the fact is worse than no morality at all.”

Preface 1, tr. R.J. Hollingdale. The German original has slightly other meaning: "das Leben ist nun einmal nicht von der Moral ausgedacht" ("...and the life was not invented, one day, by morality").
Human, All Too Human (1878)

Act I, scene II. — (Polinico).
Translation reported in Harbottle's Dictionary of quotations French and Italian (1904), p. 377.
La Calandria (c. 1507)

"The Reasons for My Involvement in the Peace Movement" (1972) http://www.shalomctr.org/node/61; later included in Moral Grandeur and Spiritual Audacity (1996)
Context: There is immense silent agony in the world, and the task of man is to be a voice for the plundered poor, to prevent the desecration of the soul and the violation of our dream of honesty.
The more deeply immersed I became in the thinking of the prophets, the more powerfully it became clear to me what the lives of the Prophets sought to convey: that morally speaking, there is no limit to the concern one must feel for the suffering of human beings, that indifference to evil is worse than evil itself, that in a free society, some are guilty, but all are responsible.

"'Moral Relativism': Do Conservatives Really Object?" https://www.nationalreview.com/2019/06/moral-relativism-absolutism-debate-conservatism/ (18 June 2019), National Review

Source: Death in the Afternoon (1932), Ch. 1

Source: 1920s, The Future of an Illusion (1927), Ch. 7

Universities, Actual and Ideal (1874)
1870s

Section 9 : Ethical Outlook
Founding Address (1876), Life and Destiny (1913)
Context: Theologians often say that faith must come first, and that morality must be deduced from faith. We say that morality must come first, and faith, to those whose nature fits them to entertain it, will come out of the experience of a deepened moral life as its richest, choicest fruit.
Precisely because moral culture is the aim, we cannot be content merely to lift the mass of mankind above the grosser forms of evil. We must try to advance the cause of humanity by developing in ourselves, as well as in others, a higher type of manhood and womanhood than the past has known.
To aid in the evolution of a new conscience, to inject living streams of moral force into the dry veins of materialistic communities is our aim.
We seek to come into touch with the ultimate power in things, the ultimate peace in things, which yet, in any literal sense, we know well that we cannot know. We seek to become morally certain — that is, certain for moral purposes — of what is beyond the reach of demonstration. But our moral optimism must include the darkest facts that pessimism can point to, include them and transcend them.

Interview by James Cameron in Picture Post (28 October 1950)
Context: If in the modern world wars have unfortunately to be fought (and they do, it seems) then they must be stopped at the first possible moment, otherwise they corrupt us, they create new problems and make our future even more uncertain. That is more than morality; it's sense.