Srimad-Bhagavatam: Canto 7 - Chapter 1 - Verse 14-15
Sanskrit:
दृष्ट्वा महाद्भुतं राजा राजसूये महाक्रतौ ।वासुदेवे भगवति सायुज्यं चेदिभूभुज: ॥ १४ ॥तत्रासीनं सुरऋषिं राजा पाण्डुसुत: क्रतौ ।पप्रच्छ विस्मितमना मुनीनां शृण्वतामिदम् ॥ १५ ॥
ITRANS:
dṛṣṭvā mahādbhutaṁ rājārājasūye mahā-kratauvāsudeve bhagavatisāyujyaṁ cedibhū-bhujaḥ
Translation:
O King, at the Rājasūya sacrifice, Mahārāja Yudhiṣṭhira, the son of Mahārāja Pāṇḍu, personally saw Śiśupāla merge into the body of the Supreme Lord, Kṛṣṇa. Therefore, struck with wonder, he inquired about the reason for this from the great sage Nārada, who was seated there. While he inquired, all the sages present also heard him ask his question.