Nonetheless, Lord Krsna accepted her as His mother, and thus she attained the destination befitting Krsna's mother. Of whom should I take shelter but Krsna, who is most merciful

Expressions researched:
"Nonetheless, Lord Kṛṣṇa accepted her as His mother, and thus she attained the destination befitting Kṛṣṇa’s mother. Of whom should I take shelter but Kṛṣṇa, who is most merciful"

Sri Caitanya-caritamrta

CC Madhya-lila

Oh, how wonderful it is! Pūtanā, the sister of Bakāsura, wanted to kill Kṛṣṇa by smearing deadly poison on her breasts and having Kṛṣṇa take it. Nonetheless, Lord Kṛṣṇa accepted her as His mother, and thus she attained the destination befitting Kṛṣṇa’s mother. Of whom should I take shelter but Kṛṣṇa, who is most merciful?

CC Madhya 22.98, Translation and Purport

Oh, how wonderful it is! Pūtanā, the sister of Bakāsura, wanted to kill Kṛṣṇa by smearing deadly poison on her breasts and having Kṛṣṇa take it. Nonetheless, Lord Kṛṣṇa accepted her as His mother, and thus she attained the destination befitting Kṛṣṇa’s mother. Of whom should I take shelter but Kṛṣṇa, who is most merciful?

This is a quotation from Śrīmad-Bhāgavatam (SB 3.2.23).