Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 3-6

Sanskrit:

नि:क्षत्रियां महीं कुर्वन् राम: शस्‍त्रभृतां वर: ।नृपाणां रुधिरौघेण यत्र चक्रे महाह्रदान् ॥ ३ ॥ईजे च भगवान् रामो यत्रास्पृष्टोऽपि कर्मणा ।लोकं सङ्ग्राहयन्नीशो यथान्योऽघापनुत्तये ॥ ४ ॥महत्यां तीर्थयात्रायां तत्रागन् भारती: प्रजा: ।वृष्णयश्च तथाक्रूरवसुदेवाहुकादय: ॥ ५ ॥ययुर्भारत तत् क्षेत्रं स्वमघं क्षपयिष्णव: ।गदप्रद्युम्नसाम्बाद्या: सुचन्द्रशुकसारणै: ।आस्तेऽनिरुद्धो रक्षायां कृतवर्मा च यूथप: ॥ ६ ॥

ITRANS:

niḥkṣatriyāṁ mahīṁ kurvanrāmaḥ śastra-bhṛtāṁ varaḥnṛpāṇāṁ rudhiraugheṇayatra cakre mahā-hradān

Translation:

After ridding the earth of kings, Lord Paraśurāma, the foremost of warriors, created huge lakes from the kings’ blood at Samantaka-pañcaka. Although he is never tainted by karmic reactions, Lord Paraśurāma performed sacrifices there to instruct people in general; thus he acted like an ordinary person trying to free himself of sins. From all parts of Bhārata-varṣa a great number of people now came to that Samanta-pañcaka on pilgrimage. O descendant of Bharata, among those arriving at the holy place were many Vṛṣṇis, such as Gada, Pradyumna and Sāmba, hoping to be relieved of their sins; Akrūra, Vasudeva, Āhuka and other kings also went there. Aniruddha remained in Dvārakā with Sucandra, Śuka and Sāraṇa to guard the city, together with Kṛtavarmā, the commander of their armed forces.

Purport:

According to Śrīla Viśvanātha Cakravartī, Śrī Kṛṣṇa’s grandson Aniruddha remained in Dvārakā to protect the city because He is originally Lord Viṣṇu’s manifestation as the guardian of the spiritual planet Śvetadvīpa.