Srimad-Bhagavatam: Canto 9 - Chapter 1 - Verse 13
Sanskrit:
कृतान्त आसीत् समरो देवानां सह दानवै: ।पार्ष्णिग्राहो वृतो वीरो देवैर्दैत्यपराजितै: ॥ १३ ॥
ITRANS:
kṛtānta āsīt samarodevānāṁ saha dānavaiḥpārṣṇigrāho vṛto vīrodevair daitya-parājitaiḥ
Translation:
Formerly, there was a devastating war between the demigods and the demons. The demigods, having been defeated, accepted Purañjaya as their assistant and then conquered the demons. Therefore this hero is known as Purañjaya, “he who conquered the residence of the demons.”