Nullius in verba (Latin for "on the word of no one" or "Take nobody's word for it") is the motto of the Royal Society. John Evelyn and other Fellows of the Royal Society chose the motto soon after the founding of the Society. The Royal Society website explains the motto thus:
It is an expression of the determination of Fellows to withstand the domination of authority and to verify all statements by an appeal to facts determined by experiment.
The phrase came from Horace's Epistle to his benefactor Maecenas, where he claims not to be devoted to any particular sect but is rather an eclectic by nature.
These are the words, forming two hexameters in the original context:
Nullius addictus iurare in verba magistri, – quo me cumque rapit tempestas, deferor hospes."
("(being) not obliged to swear allegiance to a master, wherever the storm drags me to, I turn in as a guest.")
The Asteroid belt minor planet known as 11059 Nulliusinverba is named after the expression and the phrase is widely used and cited elsewhere.