The term “the pot calling the kettle black” is usually used in the
sense of accusing someone of hypocrisy. The origins of the phrase date
back to at least the 1600s, when several writers published books or
plays which included wordplays on this theme. Despite suggestions that
the phrase is racist or nonsensical, the meaning is actually quite
obvious when one considers the conditions of a medieval kitchen.
Typically, pots and kettles were made from heavy materials like cast
iron to ensure that they would last and hold up to heat. Cast iron
tends to turn black with use, as it collects oil, food residue, and
smoke from the kitchen. Both pots and kettles would also have been
heated over an open fire in a kitchen. As a result, they would have
become streaked with black smoke despite the best cleaning efforts.
Since both are black, the pot calling the kettle black would clearly
be an act of hypocrisy. The act could also be described by “it takes
one to know one,” and it suggests a certain blindness to one's
personal characteristics. There is another explanation for the term,
involving the pot seeing its black reflection reflected in a polished
copper kettle. In this sense, the pot does not realize that it is
describing itself.
One of the earliest written instances of the phrase appears in Don
Quixote, by Cervantes. The epic book was published in the early 1600s,
and had a big influence on the English language. Numerous terms and
idioms have their roots in Don Quixote, such as “quixotic” to describe
an idealist. Shakespeare also played with the concept in one of his
plays, as did many of his contemporaries. The phrase has been twisted
and expanded over the centuries, appearing in forms like “pot, meet
kettle.”
Some people believe that the phrase is racist, since it refers to the
surface color of the objects involved. These individuals might want to
keep in mind that in a modern kitchen, the idiom might be “the pot
calling the kettle silver,” in a reference to the fact that many
modern pots and kettles are often made from polished stainless steel.
In this particular instance, skin color has nothing to do with the
idiom, except in the sense that both of the objects involved are the
same color.
Best Answer
I'm not sure I agree about 'Stand the test of time'. It is used in a different sense to the one the OP is seeking. If you are, for example, unsure whether a particular product will sell in the long run, or just be a passing fad, one would ask 'Will it stand the test of time?'.
But the OP is looking for a term which indicates that time will supply the answer as to which of two opinions is correct. For example - will a vaccine for Covid-19 prove possible? In that case 'time will tell', would seem more appropriate.