Both Uses of

proverb
in
Gulliver's Travels

There is an air of truth apparent through the whole; and indeed the author was so distinguished for his veracity, that it became a sort of proverb among his neighbours at Redriff, when any one affirmed a thing, to say, it was as true as if Mr. Gulliver had spoken it.†
Chpt Intr. *

proverb = a well-known, short saying that is thought to communicate wisdom

The captain understood my raillery very well, and merrily replied with the old English proverb, "that he doubted mine eyes were bigger than my belly, for he did not observe my stomach so good, although I had fasted all day;" and, continuing in his mirth, protested "he would have gladly given a hundred pounds, to have seen my closet in the eagle's bill, and afterwards in its fall from so great a height into the sea; which would certainly have been a most astonishing object, worthy to have the description of it transmitted to future ages:" and the comparison of Phaeton was so obvious, that he could not forbear applying it, although I did not much admire the conceit.†
Chpt 2

Definitions:

(1) (proverb as in: the well-known proverb)
a short saying -- typically well-known and accepted by many as offering good advice

The adjective, proverbial, may refer to a proverb or to anything that is well-known -- as in "It is a proverbial fish story exaggeration."
(2) (Proverbs as in: from The Book of Proverbs)
a work of wisdom literature found in both the Old Testament of the Christian Bible and the Hebrew Bible