In nullum avarus bonus, sed in se semper pessimus.
(Publilius Syrus, Sententia 234)

The greedy individual is good to no one, but to himself he is the worst.

Pron = in NOOL-loom AH-wah-roos BOH-noos sehd in say SEHM-per PEHS-sih-moos

Comment: In other words, we can only treat others the way we hold
ourselves. The flip side of that is that we cannot help others with
something (wisdom, advice, skill, etc) that we have not cultivated for
ourselves. While we often may make judgements about how individuals
treat others, at its core, a moral defect is most often a wound that
is killing the individual from the inside out.