Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 12
Sanskrit:
तस्य चापतत: कृष्णश्चक्रेण क्षुरनेमिना ।शिरो जहार राजेन्द्र सकिरीटं सकुण्डलम् ॥ १२ ॥
ITRANS:
tasya cāpatataḥ kṛṣṇaścakreṇa kṣura-nemināśiro jahāra rājendrasa-kirīṭaṁ sa-kuṇḍalam
Translation:
O best of kings, as Vidūratha fell upon Him, Lord Kṛṣṇa used His razor-edged Sudarśana disc to remove his head, complete with its helmet and earrings.