tāvad utthāya bhagavān
svān nivārya svayaḿ ruṣā
śiraḥ kṣurānta-cakreṇa
jahāra patato ripoḥ
tavat -- at that point; utthaya -- rising; bhagavan -- the Supreme Lord; svan -- His own (devotees); nivarya -- stopping; svayam -- Himself; rusha -- angrily; sirah -- the head; kshura -- sharp; anta -- whose edge; cakrena -- with His disc weapon; jahara -- severed; patatah -- attacking; ripoh -- of His enemy.
Srila Visvanatha Cakravarti Thakura explains the Lord's action as follows: If Lord Krishna had done nothing, there probably would have been a savage fight on the sacrificial grounds, and thus the whole ceremony would have been drenched in blood, spoiling the sanctified atmosphere. Therefore, in order to protect the Rajasuya sacrifice of Krishna's beloved devotee Yudhishthira, the Lord immediately severed Sisupala's head with His razor-sharp disc in such a way that not a drop of blood fell within the sacrificial grounds.