وَأَقَدْنَاهُ رَبَّ غَسَّانَ بِالْمُنْذِرِ كَرْهًا إِذْ لَا تُكَالُ الدِّمَاءُ
Meaning: We secured requital involving the king of Ghassān and al-Mundhir despite resistance, at a time when the settling of blood claims was difficult.
Aqadnāhu is associated with securing requital or blood compensation. Karhan signals unwillingness or compulsion. In lā tukālu al-dimāʾ, blood is treated metaphorically as something measured out; the commentary connects this to retaliation and the settling of blood claims.
This is a historical boast made by the poet. It should not be turned into an independent statement of legal rules governing retaliation.