I was just looking at 吾， found in 语 so I looked for some example sentences in iciba.com and found this. I guess it's correct, but it is a bit cryptic, so I'd like to check, probably from an old book or such.
Maybe a literal translation: 莫吾知也夫! no I knows also this (I)
莫吾知也夫! Alas, no one understands me! (iciba)
莫： there is no one
夫： this (person?), me
because given the English translation, I would write something different, perhaps: