If you have a mind to be a good champion, be quiet in a great man’s house; be surly in the narrow pass.
Do not beat your hound without a cause; do not bring a charge against your wife without having knowledge of her guilt; do not hurt a fool in fighting, for he is without his wits.
Do not find fault with high-up persons; do not stand up to take part in a quarrel; have no dealings with a bad man or a foolish man.
Let two-thirds of your gentleness be showed to women and to little children that are creeping on the floor, and to men of learning that make the poems, and do not be rough with the common people.
Do not give your reverence to all; do not be ready to have one bed with your companions.
Do not threaten or speak big words, for it is a shameful thing to speak stiffly unless you can carry it out afterwards.
Do not forsake your lord so long as you live; do not give up any man that puts himself under your protection for all the treasures of the world.
Do not speak against others to their lord, that is not work for a good man.
Do not be a bearer of lying stories, or a tale-bearer that is always chattering.
Do not be talking too much; do not find fault hastily; however brave you may be, do not raise factions against you.
Do not be going to drinking-houses, or finding fault with old men; do not meddle with low people; this is right conduct I am telling you.
Do not refuse to share your meat; do not have a niggard for your friend; do not force yourself on a great man or give him occasion to speak against you.
Hold fast to your arms till the hard fight is well ended.
Do not give up your opportunity, but with that follow after gentleness.
Source: Gods and Fighting Men – The Story of the Tuatha De Danaan and of the Fianna of Ireland. Lady Augusta Gregory 1904. www.sacred-texts.com/neu/celt/gafm/