In obedience to the command of His friend, Lord Śrī Kṛṣṇa entered the arena of the Battlefield of Kurukṣetra between the soldiers of Arjuna and Duryodhana, and while there He shortened the life spans of the opposite party by His merciful glance. This was done simply by His looking at the enemy. Let my mind be fixed upon that Kṛṣṇa.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
सपदि सखिवचो निशम्य मध्ये निजपरयोर्बलयो रथं निवेश्य । स्थितवति परसैनिकायुरक्ष्णा हृतवति पार्थसखे रतिर्ममास्तु
sapadi sakhivaco niśamya madhye nijaparayorbalayo rathaṃ niveśya | sthitavati parasainikāyurakṣṇā hṛtavati pārthasakhe ratirmamāstu
SB 1.9.35