Srimad Bhagvata Mahapurana: Book 1: Chapter 7: Verses 49-58
Suta went on : King Yudhisthira, the son of Dharma (the god of virtue), O holy Brahmanas, greeted the queen's words, which were pious and fair, compassionate, guileless, impartial and noble. Nakula and Sahadeva,Yuyudhana (Satyaki), Arjuna, the divine Sri Krsna (the son of Devaki) Himself and all other men and women (who happened to be there) endorsed what she said. On that occasion Bhima indignantly (intervened and) said, "For him who wantonly murdered sleeping youngsters without any gain either to himself or to his master death has been declared as a boon." Hearing the words of Bhima as well as of Draupadi, Lord Sri Krsna (who was distinguished by His four arms) looked into the face of his friend (Arjuna) and uttered the following words, as though smilingSri Krsna said: Even a fallen Brahmana ought not to be slain and a ruffian surely deserves to be killed. Both these precepts have been taught by Me in the scriptures. Therefore,carry out both these commands of Mine. Redeem the promise you made while consoling your beloved consort; at the same time do what is agreeable to Bhimasena and Draupadi (the daughter of the king of Pancala) as well as to Myself.
Suta says : Arjuna instantly understood the mind of Sri Hari, and with his sword cut off the gem on the Brahmana's head along with his locks. Releasing Aswatthama, who had been bound with cords and put out of countenance by the murder of boys, and who was now deprived of his splendour and gem also, Arjuna expelled him from his camp. Shaving the head (as a token of disgrace), seizure of property and expulsion from a place (where one happens to be) this is the form of capital punishment prescribed for fallen Brahmanas; there is no other corporeal form of capital punishment for them. The sons of Pandu along with Krsna (Draupadi), who were all stricken with grief at the loss of their sons, performed the cremation and other funeral rites in respect of their departed kinsmen.
Thus ends the seventh discourse entitled the"Chastisement of Aswatthama (Drona's son) in Book One of the great and glorious Bhagavata-Purana, otherwise known as the Paramahamsa-Samhita