Part 10 of The Metrical Dindshenchas

CARN FURBAIDE

Here stands the Carn of Cathbad's grandson against whom a nimble weapon was wielded; Furbaide's heath-clad grave, martial monument of a glorious soldier.
Huge was Furbaide, surnamed Fer Benn, son to comely Conchobar: Ethne, whom verses extol, was his mother, the sister of Medb and Clothru.
Ethne came to the pleasant province and made her home with Conchobar: when they lived together there Furbaide was begotten by him.

Presently Ethne journeys from the east to be delivered in Mag Cruachan: Lugaid came to meet her at the fairy plain of Bun Silenn.
Lugaid committed a foul crime upon shapely Conchobar's wife: he drew her son forth from her side after drowning her in ripe pregnancy.
[From her is named thenceforth the river that is called Ethne; from the woman—'tis no grudging secret—the river bears the name of Ethne.]
Therefore the name Fer Bend clave to Furbaide—bright his hue: two horns grew on the head of staunch illustrious Furbaide.
Seventeen years was his age, the fame of his wisdom was spread through Erin: he broke a breach of three hundred (no hidden feat!) in the battle at Ilgáirech.
He planned in his proud heart to go and avenge his mother: and by his hand fell the mother of Lugaid Three-Stripes—martial the exploit.
Came Lugaid, a fasting journey, in pursuit from the west; and smooth-skinned Fer Bend fell by his hand on the crest of Sliab Ullenn.

A stone for every man that the axe clove—so was the carn built: the king's son died in revenge for a woman: that is the origin of the Carn.
The head was presently brought eastward to bear it to Conchobar's house: and there fell from Lugaid's fist the tooth of the much lamented youth.
Ullenn Red-blade found it, red-cloaked Find ua Baiscne's son: he came from a far distance, bent on war, and on that mountain did expire.
Heaven's King, maker of all that is, nobler is he than all high kings: King, till doomsday come with loud acclaim, high over all is He!