दृष्ट्वाग्न्यागार आसीनम् आवेशितधियं मुनिम् ।
भगवत्युत्तमश्लोके जघ्नुस्ते पापनिश्चयाः ॥ ११ ॥
drstva-by seeing; agni-agare-at the place where the fire sacrifice is performed; asinam-sitting; avesita-completely absorbed; dhiyam-by intelligence; munim-the great sage Jamadagni; bhagavati-unto the Supreme Personality of Godhead; uttama-sloke-who is praised by the best of selected prayers; jaghnuh-killed; te-the sons of Kartaviryarjuna; papa-niscayah-determined to commit a greatly sinful act, or the personified sins.
The sons of Kartaviryarjuna were determined to commit sinful deeds. Therefore when they saw Jamadagni sitting by the side of the fire to perform yajna and meditating upon the Supreme Personality of Godhead, who is praised by the best of selected prayers, they took the opportunity to kill him.