“It is too easy to destroy and ruin a good relationship. Just a few harsh words, just a few bad deeds.”
Related quotes

“Harshness is for the good of a boy, soft-heartedness will ruin him.”
Book V, ch. 5.
The Japanese Family Storehouse (1688)

“Words are like spices. Too many is worse than too few.”
Source: The Last Slice of Rainbow and Other Stories

Response to Walter Mason Camp when asked how long the fighting took on Custer Hill, in [Fox, Richard A., Archaeology, History, and Custer's Last Battle: The Little Big Horn Reexamined, February 16, 2015, University of Oklahoma Press, 9780806129983, 195, https://books.google.com/books?id=5tazBgAAQBAJ, 1 March 2018]

“Few sons, indeed, are like their fathers.
Generally they are worse; but just a few are better.”
II. 276–277 (tr. E. V. Rieu).
Odyssey (c. 725 BC)
Source: The Odyssey

“Few people remember good women. They don't forget bad girls.”
" "Be Good And Be Forgotten," Says Star https://trove.nla.gov.au/newspaper/article/48485193?searchTerm=joan+bennett+hiss" (1946)

“To be good, and to do good, is the whole duty of man comprised in a few words.”
Letter to Elizabeth Shaw (1784), quoted in John Adams (2001) by David McCullough, p. 310

Quoted in The Montreal Weekly Star (22 August 1885), and War in the West : Voices of the 1885 Rebellion (1985) by Rudy Henry Wiebe and Bob Beal, p. 2