tad asau vadhyatāṁ pāpa ātatāyy ātma-bandhu-hā bhartuś ca vipriyaṁ vīra kṛtavān kula-pāṁsanaḥ
Synonyms
tat—therefore; asau—this man; vadhyatām—the sinner; pāpaḥ—assaulter; ātatāyī—own; ātma—killer of sons; bandhu-hā—of the master; bhartuḥ—also; ca—having not satisfied; vipriyam—oh the warrior; vīra—one who has done it; kṛtavān—the burnt remnants of the family.
Translation
Therefore this man is the assaulter and murderer of your won family members. Not only that he has also dissatisfied his master and is also the burnt remnants of his family. Kill him immediately.
Purport
The son of Dronacharya is condemned here as the burnt remnants of his family. The good name of Dronacharya is very much respectful. Although he joined the enemy camp still Dronacharya was held always respectful for the Pandavas and Arjuna saluted him before beginning the fight with Dronacharya even. There was nothing wrong in that way. But the son of Dronacharya degraded himself from family's good name for doing acts which are never done by the Dwijas or the twice-born higher castes. Aswathwama the son of Dronacharya commited murder by killing five sleeping sons of Droupadi by whieh he dissatisfied his master Duryodhan who never approved of the heinous act of killing the five sleeping sons of the Pandvas. This means that Aswathama became an assaulter of Arjuna's own family members and as such he was liable to be punished by him. In the Sastras, the atataee, who attacks without notice or kills from the back or one who sets fire in another's house or kidnapes one's wife,—is condemned to death and these facts are reminded by Krishna to Arjuna so that he might take notice of these facts and do the needful.