Lezoux Plate
The Lezoux plate is a ceramic plate discovered in 1970 at Lezoux, which contains one of the longer texts in the Gaulish language which has yet been found. Since it is fragmentary, only parts of the text can be read, and only a fragment of that can be reliably translated. From those bits, it seems to be a list of aphorisms directed toward a young man.
The last form, -breto is likely related to Old Irish bráth "judgement" but the vowel is unexpected.