Śrīmad-Bhāgavatam · Text 8.3.1
Who is speaking and story frame
श्रीबादरायणिरुवाच
एवं व्यवसितो बुद्ध्या समाधाय मनो हृदि ।
जजाप परमं जाप्यं प्राग्जन्मन्यनुशिक्षितम् ॥ १ ॥
śrī-bādarāyaṇir uvāca
evaṁ vyavasito buddhyā
samādhāya mano hṛdi
jajāpa paramaṁ jāpyaṁ
prāg-janmany anuśikṣitam
Śrī Śukadeva Gosvāmī continued: Thereafter, the King of the elephants, Gajendra, fixed his mind in his heart with perfect intelligence and chanted a mantra which he had learned in his previous birth as Indradyumna and which he remembered by the grace of Kṛṣṇa.
Read Śrīla Prabhupāda's purport on Vedabase.io