user21235: Can someone provide me a reference to the passage in the canon where the Buddha describes the length of a kalpa?
In the English Wikipedia article there is this quote which is allegedly by the Buddha:

"Were a man to take a piece of cloth of this most delicate texture [of
fine cotton], and therewith to touch in the slightest possible manner,
once in a hundred years, a solid rock, free from earth, a yojana [~14
miles] high, and as much broad, the time would come when it would be
worn down, by this imperceptible trituration, to the size of a mung or
undu seed. This period would be immense in its duration; but it has
been declared by Buddha that it would not be equal to a Maha Kalpa."

I would like to find that exact passage but alas no luck. I don't know where this could be. In the wiki article the sutta nipata is mentioned but I couldn't find anything in there.
Thank you.

user471: This seems to be from SN 15.5. You can find similar similes in other suttas of SN 15. SN is samyutta nikaya, in this case, not sutta nipata.

Then a mendicant went up to the Buddha, bowed, sat down to one side,
and asked him, “Sir, how long is an eon?”
“Mendicant, an eon is long. It’s not easy to calculate how many years,
how many hundreds or thousands or hundreds of thousands of years it
lasts.”
“But sir, is it possible to give a simile?”
“It’s possible,” said the Buddha.
“Suppose there was a huge stone mountain, a league long, a league
wide, and a league high, with no cracks or holes, one solid mass. And
as each century passed someone would stroke it with a fine cloth from
Kāsī. By this means the huge stone mountain would be worn away before
the eon comes to an end. That’s how long an eon is. And we’ve
transmigrated through many such eons, many hundreds, many thousands,
many hundreds of thousands.
Why is that? Transmigration has no known beginning. … This is quite
enough for you to become disillusioned, dispassionate, and freed
regarding all conditions.”
SN 15.5


21235: <p>Can someone provide me a reference to the passage in the canon where the Buddha describes the length of a kalpa?</p>
<p>In the English Wikipedia article there is this quote which is allegedly by the Buddha:</p>
<blockquote>
<p>&quot;Were a man to take a piece of cloth of this most delicate texture [of
fine cotton], and therewith to touch in the slightest possible manner,
once in a hundred years, a solid rock, free from earth, a yojana [~14
miles] high, and as much broad, the time would come when it would be
worn down, by this imperceptible trituration, to the size of a mung or
undu seed. This period would be immense in its duration; but it has
been declared by Buddha that it would not be equal to a Maha Kalpa.&quot;</p>
</blockquote>
<p>I would like to find that exact passage but alas no luck. I don't know where this could be. In the wiki article the sutta nipata is mentioned but I couldn't find anything in there.</p>
<p>Thank you.</p>
 471: <p>This seems to be from <a href="https://suttacentral.net/sn15.5/en/sujato" rel="nofollow noreferrer">SN 15.5</a>. You can find similar similes in other suttas of <a href="https://suttacentral.net/sn15" rel="nofollow noreferrer">SN 15</a>. SN is samyutta nikaya, in this case, not sutta nipata.</p>
<blockquote>
<p>Then a mendicant went up to the Buddha, bowed, sat down to one side,
and asked him, “Sir, how long is an eon?”</p>
<p>“Mendicant, an eon is long. It’s not easy to calculate how many years,
how many hundreds or thousands or hundreds of thousands of years it
lasts.”</p>
<p>“But sir, is it possible to give a simile?”</p>
<p>“It’s possible,” said the Buddha.</p>
<p>“Suppose there was a huge stone mountain, a league long, a league
wide, and a league high, with no cracks or holes, one solid mass. And
as each century passed someone would stroke it with a fine cloth from
Kāsī. By this means the huge stone mountain would be worn away before
the eon comes to an end. That’s how long an eon is. And we’ve
transmigrated through many such eons, many hundreds, many thousands,
many hundreds of thousands.</p>
<p>Why is that? Transmigration has no known beginning. … This is quite
enough for you to become disillusioned, dispassionate, and freed
regarding all conditions.”<br />
<a href="https://suttacentral.net/sn15.5/en/sujato" rel="nofollow noreferrer">SN 15.5</a></p>
</blockquote>
