Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 28

Sanskrit:

एतावदुक्त्वा भगवान् निवृत्तोऽसद्वधादपि ।भावित्वात् तं कुशाग्रेण करस्थेनाहनत् प्रभु: ॥ २८ ॥

ITRANS:

etāvad uktvā bhagavānnivṛtto ’sad-vadhād apibhāvitvāt taṁ kuśāgreṇakara-sthenāhanat prabhuḥ

Translation:

[Śukadeva Gosvāmī continued:] Although Lord Balarāma had stopped killing the impious, Romaharṣaṇa’s death was inevitable. Thus, having spoken, the Lord killed him by picking up a blade of kuśa grass and touching him with its tip.

Purport:

Śrīla Prabhupāda writes: “Lord Balarāma had avoided taking part in the Battle of Kurukṣetra, and yet because of His position as an incarnation, the reestablishment of religious principles was His prime duty. Considering these points, He killed Romaharṣaṇa Sūta simply by striking him with a kuśa straw, which was nothing but a blade of grass. If someone questions how Lord Balarāma could kill Romaharṣaṇa Sūta simply by striking him with a blade of kuśa grass, the answer is given in the Śrīmad-Bhāgavatam by the use of the word prabhu, ‘master.’ The Lord’s position is always transcendental, and because He is omnipotent He can act as He likes without being obliged to follow the material laws and principles. Thus it was possible for Him to kill Romaharṣaṇa Sūta simply by striking him with a blade of kuśa grass.”