adyānena mahā-vyālo
yaśodā-nanda-sūnunā
hato 'vitā vayaṁ cāsmād
iti bālā vraje jaguḥ
adya - today; anena - by Him; mahā-vyālaḥ - a great serpent; yaśodā - of Yaśodā; nanda - and Mahārāja Nanda; sūnunā - by the son; hataḥ - has been killed; avitāḥ - have been saved; vayam - we; ca - and; asmāt - from that demon; iti - thus; bālāḥ - the boys; vraje - in Vṛndāvana; jaguḥ - sang.
Actually, Lord Kṛṣṇa had killed the demon Aghāsura one year earlier, but the boys, bewildered by the mystic potency of Brahmā for one year, did not notice the time passing and thus thought that on that very day Lord Kṛṣṇa had killed the demon Aghāsura and was now returning home with them.