In Search of the Miraculous (1949)
Context: In properly organized groups no faith is required; what is required is simply a little trust and even that only for a little while, for the sooner a man begins to verify all he hears the better it is for him. <!-- Ch. 11, p. 288
“Trust, but Verify.”
This was a signature phrase of Ronald Reagan — he used it dozens of times in public, although he was not the first person known to use it. When Reagan used this phrase, he was usually discussing relations with the Soviet Union and he almost always presented it as a translation of the Russian proverb "doveriai, no proveriai". See also Trust, but verify at Wikipedia.
Misattributed
Variant: Trust, but Verify.
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Ronald Reagan 264
American politician, 40th president of the United States (i… 1911–2004Related quotes

“Never trust them, never trust them. They can't be trusted.”
On the Germans, to Woodrow Wyatt (16 November 1991), as quoted in The Journals of Woodrow Wyatt: Volume Two (2000) by Woodrow Wyatt, p. 608

“Trust nobody, TRUST NO BODY.”
1990s, Prison interviews and interrogations (1995)

Youtube, Other, Faith is not a virtue https://www.youtube.com/watch?v=uDal8b6-X5o (June 20, 2012)

“The man who trusts womankind trusts deceivers.”
Source: Works and Days (c. 700 BC), line 375.

“When we give trust, we receive trust. And people who trust us pay attention to us.”
Source: Women Can't Hear What Men Don't Say (2000), p. 33.