Mahabharata 1.136.4

1.136.4

āyudhāgāramādīpya dagdhvā caiva purocanam |
ṣaṭprāṇino nidhāyeha dravāmo'nabhilakṣitāḥ || 4 ||

"Vaisampayana said, 'Seeing the Pandavas living there cheerfully and without suspicion for a full year, Purochana became exceedingly glad. And beholding Purochana so very glad, Yudhishthira, the virtuous son of Kunti, addressing Bhima and Arjuna and the twins (Nakula and Sahadeva) said, 'The cruel-hearted wretch hath been well-deceived. I think the time is come for our escape. Setting fire to the arsenal and burning Purochana to death and letting his body lie here, let us, six persons, fly hence unobserved by all!'