This poem comes from the Silva distichorum moralium by François Oudin (1719).
Qui Recta Monent
Semper ama qui recta monent; hos semper amicos
Crede tibi, vel dum forsan acerba monent.
The vocabulary is keyed to the DCC Latin Vocabulary list. There are two words in this poem that are not on the DCC list:
acerbus, -a, -um: bitter, harsh, grievous
forsan: perhaps, perchance
amīcus -a -um: friendly; (as subst.) friend
amō -āre: to love; amans -ntis m./f.: lover
crēdō crēdere crēdidī crēditum: believe
dum: while (+ indic.); until (+ subj.); provided that (+ subj.)
hic haec hoc: this; hōc: on this account
moneō monēre monuī monitum: warn, advise
qui quae quod: who, which, what / quis quid: who? what? which?
rectus -a -um: straight, direct
semper: always, ever
tū tuī tibi tē: you (sing.)
vel: or else, or; even; vel . . . vel: either… or