Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 15

Sanskrit:

वृक्णे स्वशूले बहुधारिणा हरे:प्रत्येत्य विस्तीर्णमुरो विभूतिमत् ।प्रवृद्धरोष: स कठोरमुष्टिनानदन् प्रहृत्यान्तरधीयतासुर: ॥ १५ ॥

ITRANS:

vṛkṇe sva-śūle bahudhāriṇā hareḥpratyetya vistīrṇam uro vibhūtimatpravṛddha-roṣaḥ sa kaṭhora-muṣṭinānadan prahṛtyāntaradhīyatāsuraḥ

Translation:

The demon was enraged when his trident was cut to pieces by the discus of the Personality of Godhead. He therefore advanced toward the Lord and, roaring aloud, struck his hard fist against the Lord’s broad chest, which bore the mark of Śrīvatsa. Then he went out of sight.

Purport:

Śrīvatsa is a curl of white hair on the chest of the Lord which is a special sign of His being the Supreme Personality of Godhead. In Vaikuṇṭhaloka or in Goloka Vṛndāvana, the inhabitants are exactly of the same form as the Personality of Godhead, but by this Śrīvatsa mark on the chest of the Lord He is distinguished from all others.