I found this poem in the collection Philosophia Patrum edited by Julius Wegeler.
Mortis Mors
Mors mortis morti mortem nisi morte dedisset,
Caelorum nobis ianua clausa foret.
The vocabulary is keyed to the DCC Latin Vocabulary list. There is only one word in this poem that is not on the DCC list:
iānua (iānuae, f.): door, doorway
caelum -ī n.: sky, heavens
claudō claudere clausī clausum: close, shut
dō dare dedī datum: give
mors mortis f.: death
nisi/nī: if not, unless
nōs nostrum/nostrī nobis nōs: we
