SB 10.6.30

śrī-śuka uvāca
iti praṇaya-baddhābhir
 gopībhiḥ kṛta-rakṣaṇam
pāyayitvā stanaṁ mātā
 sannyaveśayad ātmajam
Synonyms: 
śrī-śukaḥ uvāca — Śrī Śukadeva Gosvāmī said; iti — in this way; praṇaya-baddhābhiḥ — who were bound with maternal affection; gopībhiḥ — by the elderly gopīs, headed by mother Yaśodā; kṛta-rakṣaṇam — all measures were taken to protect the child; pāyayitvā — and after that, feeding the child; stanam — the nipple; mātā — mother Yaśodā; sannyaveśayat — made to lie down on the bed; ātmajam — her son.
Translation: 
Śrīla Śukadeva Gosvāmī continued: All the gopīs, headed by mother Yaśodā, were bound by maternal affection. After they thus chanted mantras to protect the child, mother Yaśodā gave the child the nipple of her breast to suck and then got Him to lie down on His bed.
Purport: 

When a baby drinks milk from the breast of his mother, this is a good sign of health. So the elderly gopīs were not satisfied with chanting mantras to give protection to Kṛṣṇa; they also tested whether their child’s health was in order. When the child sucked the breast, this confirmed that He was healthy, and when the gopīs were fully satisfied, they had the child lie down on His bed.