I've seen the quote below attributed to Einstein in several places
Do not worry about your difficulties in mathematics, I assure you that mine are greater.
Even on sites where several other Einstein quotes are sourced (for example here) this quote is not given a source.
It seems like it is a genuine Einstein quote, but I would like to know about the broader context for the quote. I like it because I've always interpreted it to mean something like "to learn math is to struggle with math." The addressee was probably struggling with algebra or calculus while Einstein was probably struggling with differential geometry (since he was famously not as good at it as, for example, Hilbert). But the point is that no one is so smart that every mathematical topic comes easily. That said, I have no idea if this was the spirit of the quote since I have no source for it.
Is there a known source for this quote, or is it just something Einstein is known to have said at some point?