Non Omnibus Credas
Tempore non omni non omnibus omnia credas;
Qui misere credit, creditur esse miser.
Source: Anonymus Neveleti (12th century), 24; it goes with the fable of the wolf and the sow. Meter: Elegiac. Note the nice play on the active credit, "he puts faith in, he trusts" and the passive creditur, "he is believed (to be)."
You should not believe everyone (non credas omnibus) in all things (omnia) at all times (tempore omni); he who (qui) miserably believes (misere credit) is believed to be miserable (creditur esse miser).
The vocabulary is keyed to the DCC Latin Vocabulary list. All the words in this poem are on that list:
crēdō crēdere crēdidī crēditum: believe
miser misera miserum: wretched, pitiable
omnis -e: all, every, as a whole
qui quae quod: who, which, what / quis quid: who? what? which?
sum, esse, fuī: be, exist
tempus -oris n.: time