TBH after reading that it still sounds like JP Morgan or Roosevelt is a safe attribution choice there. The particular structure of the sentence combined with "commonly used by" or "made popular by", etc is sufficient IMO. Quote sourcing is always a bit vague.
Or maybe just saying "as the commonly used phrase goes" is better.
I don't entirely disagree, but I feel like quotations are so often used in discourse without any context, and with a problematic sort of "pure" attribution to the genius of the person quoted. Quotations from Einstein or Lincoln are frequent examples of this, even where the quote is not misattributed.
Of course, blatant misattribution is also so dang common that it seems better to me in general to cite some kind of context or whatever. Plus (for me, a prior editor) use of quote marks typically implies verbatim, citable quotation, so that's a factor whether the attribution is "safe", as you suggest.
Not to criticize anything here at all; I just wanted to throw in some of that sweet sweet context!
Or maybe just saying "as the commonly used phrase goes" is better.