Daiva here means "belonging to deva, the Lord." The cows and cowherd boys, whose intellignce was covered by the lord’s lila sakti (daiva upahata cetasah), , appeared to lose their lives (though they are eternal). Actually, they were covered by the yogamaya of the Lord for the purpose of perfecting pastimes.

This verse explains that the arrangements were made by the power of the Lord’s śakti in charge of future pastimes. The boys had their knowledge taken away by the influence of the Lord’s līlā-śakti (daiva). It may be explained as īśa-ceṣṭitaḥ, acts that only the Lord can perform. (SB 10.15.19) Just by sipping that water they fell down as if lifeless. The word “poison” is repeated from the last verse to indicate the strength of the poison. The boys were as if without life since the cause was the arrangement of the Lord. Vai means immediately. He immediately glanced at them since they were completely dependent on him (svanāthān), showering nectar just like material nectar which gives life to material people. His glance however was a shower of mercy upon the boys and cows since his mercy was their very life. Or he showered tears of mercy as nectar as is said in the Second Canto: yad vai vraje vraja-paśūn viṣa-toya-pītān pālāṁs tv ajīvayad anugraha-dṛṣṭi-vṛṣṭyā | He will bring to life the cows and cowherds who drank the poisonous water by the shower of his merciful, sweet glance. SB 2.7.28 He brought them to life completely (samajīvayat)-- by also removing their fatigue and lamentation. That power was not artificial, but natural since he is yogeśvareśvaraḥ, the master among masters of yoga. Masters of yoga get their powers by worshipping him.

Drinking the water in Kṛṣṇa’s absence by being afflicted by thirst because of the heat was the desire of Kṛṣṇa in order to drive Kāliya from the lake. This becomes clear late. Thus it is said here that their knowledge was overcome by the will of the Lord or the will of Kāliya (daivopahata-cetasaḥ). They slightly sipped the water (upaspṛśya) or touched the edge of the water. This is repetition of the statement of the last verse, in order to strengthen the impression of the act. Or it emphasizes the poison as the cause. All the cows and cowherds fell down at the edge of the water. Or they fell into the svarūpa of water (they became unconscious like water). Because they immediately fell down on drinking the poison water, they could not go elsewhere. All of this is the remarkable action of the Lord. The Lord is later called “astonishing in his actions” (adbhūta-karmaṇā). (SB 1016.63) This will be elaborated at that time. O you who give joy to the kurus! Śukadeva gives comfort to the Parīkṣit who was lamenting. Looking at all the people in that condition (tān tathā-bhūtan) without delay (vai), he brought them to life. The specific condition is not mentioned because it was inauspicious and unsuitable to repeat the description. Or suddenly Śukadeva felt a manifestation of affection. He glanced immediately, with a glance of the greatest affection (amrṭa-varṣiṇyā), a shower of nectar, because they had no other shelter (sva-nāthān). This could only be accomplished by the will of Kṛṣṇa. He brought them back to a healthy condition (ajīvayat) all at the same time, removing completely (sam) all fatigue and sorrow, because Kṛṣṇa was the sole friend of the people of Vraja and suffered their suffering. This is not astonishing because he is the lord of all masters of yoga. All of the yogīs’ powers arise from a small portion of his powers. Or if he protects the yogīs, how much more he will protect the people of Vraja.