PL 51, col. 92

Carmen de ingratis (Prosper Aquitanus), J. P. Migne

Quos si tranquilla studeas cognoscere cura,
Tutus ab adverso turbine, lector, eris,
Nec libertate arbitrii rapiere rebellis,
Ulla nec audebis dona negare Dei.

Text from the Corpus Corporum (University of Zurich).