«أَنْ لَيْسَ يُغْنِي عَنْكَ فِي الْمَضَائِقِ، إِلَّا إِذَا فَرَّ فِرَارَ الْآبِقِ»
In hardship, the coin helps you only when it flees from you like an absconding servant.
Laysa negates usefulness, and illā idhā narrows the useful condition: money helps in hardship when it is spent. The negative-plus-exception pattern gives the proposition rhetorical force.
Farra firār al-ābiq intensifies the escape image, likening departing cash to a runaway servant. The coin itself has not changed; the speaker selects a contrary aspect for blame after praising it.