Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 44

Sanskrit:

रुरोध मथुरामेत्य तिसृभिर्म्‍लेच्छकोटिभि: ।नृलोके चाप्रतिद्वन्द्वो वृष्णीन्श्रुत्वात्मसम्मितान् ॥ ४४ ॥

ITRANS:

rurodha mathurām etyatisṛbhir mleccha-koṭibhiḥnṛ-loke cāpratidvandvovṛṣṇīn śrutvātma-sammitān

Translation:

Arriving at Mathurā, this Yavana laid siege to the city with thirty million barbarian soldiers. He had never found a human rival worth fighting, but he had heard that the Vṛṣṇis were his equals.

Purport:

Śrīla Viśvanātha Cakravartī quotes from the Viṣṇu Purāṇa concerning the history of Kālayavana: “Once, Gārgya was ridiculed by his brother-in-law as a eunuch, and when the Yādavas heard this they laughed heartily. Infuriated by their laughter, Gārgya set out for the south, thinking, ‘May I have a son who will bring terror to the Yādavas.’ He worshiped Lord Mahādeva, eating powdered iron, and after twelve years obtained his desired benediction. Elated, he returned home. “Later, when the childless King of the Yavanas requested a son from him, Gārgya begot in the Yavana’s wife a son, Kālayavana. Kālayavana possessed the fury of Lord Śiva in his aspect as Mahākāla. Once, Kālayavana asked Nārada, ‘Who are now the strongest kings on earth?’ Nārada replied that the Yadus were. Thus sent by Nārada, Kālayavana appeared at Mathurā.”