Author eludes me too. Even though I have all but 3 letters of name, I can’t get it.
Googling the quote should give you the author. Apparently H.625 is a date, not a citation, i.e., chapter or verse. The author was once believed to have lived in the seventh century AD, but according to his wikipedia entry that is disputed, and his work may be dated not later than 450 AD.
FWIW, the author’s wikipedia entry identifies him as a philosopher, who wrote a grammar, and also attributed to the same author is a body of aphoristic poetry (example above) which may or may not be by the same author.
” ……but the source of the quote eludes me”
You could try google-searching on the quote itself.