The Carmen Saliare is a fragment of archaic Latin, which played a part in the rituals performed by the Salii (Salian priests, a.k.a. "leaping priests") of Ancient Rome. There are 35 extant fragments of the Carmen Saliare, which can be read in Morel's FPL.
The rituals revolved around Mars and Quirinus, and were performed in March and October. These involved processions in which they donned archaic armour and weapons, performed their sacred dance, and sang the Carmen Saliare. As a body they existed before the founding of the Roman Republic, tracing their origin back to the reign of Numa Pompilius. The Salian priests were chosen from the sons of patrician families whose parents were still living. They were appointed for life, though they were allowed to resign from the Salian priesthood if they achieved a more prestigious priesthood or a major magistracy.
Fragments 1 and 3 of the hymn have been preserved by Marcus Terentius Varro in his De Lingua Latina, 7.26, 27, and fragment 2 by Quintus Terentius Scaurus in his De orthographia. They say:
cume tonas, Leucesie, prae tet tremonti
+quot+ ibet etinei de is cum tonarem
...cozeulodorieso.
Omnia vero adpatula coemisse.
Ian cusianes duonus ceruses dunus Ianusve
vet pom melios eum recum.
When thou thunderest, O God of light, they tremble before thee!
All gods beneath thee have heard thee thunder!
...
but to have acquired all that is spread out
Now the good ... of Ceres ... or Janus
...
or
The interpretation of the text has posed difficulties. The Latin words that are easily recognizable in it appear to mention thunder, Janus, and Ceres. Even in the first century BC, Cicero was unable to interpret much of the chant.