The Jataka, Vol. III, tr. by H.T. Francis and R.A. Neil, , at sacred-texts.com
"Wounding another," etc.—This story was told by the Master when he was at Jetavana, about the family priest of the king of Kosala, who, it is said, as he was driving in his chariot to a village on his estate came upon a caravan in a narrow road, and crying out once and again, "Out of the way with you," was so enraged at a cart not clearing out of his way that he threw his goad-stick at the driver of the first cart. The stick struck against the yoke of the chariot, and rebounding hit him on the forehead and raised a bump on his head. The priest turned back and went and told the king he had been wounded by some carters. The carters were summoned, and the judges examining into the case found the priest only was to blame. One day the matter was discussed in the Hall of Truth, 
how that the king's chaplain, who said he had been assaulted by some carters, on going to law was cast in his suit. When the Master came and inquired what the Brethren were sitting in council to discuss, on hearing what it was he said, "Not now only, Brethren, but formerly also this fellow acted in precisely the same way." And he then told them a story of the olden time.
Once upon a time when Brahmadatta was reigning in Benares, the Bodhisatta became his lord justice. The king's chaplain drives to a village where he was headman, and acts in exactly the same way as in the other tale, but in this version, when the king heard the priest's story, he summoned the carters and himself sat in judgment, and without examining into the matter he said, "You have beaten my priest and raised a bump on his forehead," and ordered all their property to be taken from them. Then said the Bodhisatta to him, "Sire, without even investigating the matter you order them to be mulcted of all their goods, but some men after inflicting wounds on themselves declare that they have been wounded by another. Therefore it is wrong for one who bears rule to act thus without trying the case. He ought not to act till he has heard everything." And then he recited these verses:
Himself the smiter, he complains of blows.
Wise men, O king, of partial views beware,
Hear both sides first, then judgment true declare.
The idle sensual layman I detest,
The false ascetic is a rogue confest.
A bad king will a case unheard decide,
Wrath in the sage can ne’er be justified.
 The warrior prince a well-weighed verdict gives,
Of righteous judge the fame for ever lives.
The king on hearing the words of the Bodhisatta judged righteously, and when the case was duly tried, the blame was found to rest with the brahmin alone.
The Master, his lesson ended, identified the Birth: "The Brahmin played the same part in both stories, and I myself was the wise minister in those days."