According to the NB column in the May 28 TLS , the first recorded example of a limerick meter and rhyme occurs in a 13th-century prayer:
Si vitiorum meorum evacuatio
Concupiscentiae et libidinis exterminatio,
Caritatis et patientiae,
Humilitatis et obedientiae,
Omniumque virtutum augmentatio .
As NB goes on to say, “It is a curiosity of literary history (first recorded here, we dare say) that the earliest application of the limerick metre should have occurred in a plea to resist all that the limerick became famous for.