There is no known source for this quote from Marx's writings or speeches.
It's possible that the quote is:
* Misattributed: It may be a paraphrase of a similar idea expressed by Marx, but not his exact words.
* A paraphrase: The quote may be a summary of a broader idea that Marx expressed in his works.
* A misremembered quote: Sometimes quotes are misremembered or changed over time.
It's always best to verify the source of a quote before accepting it as accurate.