Srimad Bhagvata Mahapurana: Book 10: Chapter 13: Verses 34-44
Highly gratified by embracing the young ones, the elderly cowherds slowly departed from that place with (great) difficulty, tears gushing forth (from the eyes) at their very thought. Perceiving the longing induced by abundance of love every moment on the part of the people and the cows of Vraja even for their offspring (long) weaned from the mother's breast, Balarama, who failed to discover its cause, thought as follows:- 'What a wonder it is that the love of (the whole of) Vraja including myself towards the children is growing (in intensity) as it never did before and (even) as it did (in the past) for Sri Krsna (the Son of Vasudeva), the Soul of the universe! What is this enchantment and whence has it come? IS it the work of some god, of a human being or a demon ? In all probability it must be the deluding potency of my Lord (Sri Krsna) and none other, for it has deluded even me (which no other Maya can)." Pondering thus, Balarama who belonged to the race of the Yadus (who were also known as the Dasarhas), saw through his intuitional eye all the calves as well as his companions to be (none else than) Lord Visnu. (Turning to Sri Krsna, he said), "These cowherd boys are not the rulers of gods nor are these calves Rsis (as I knew them to be); You alone appear, 0 Lord, even in these different forms. (Pray,) relate You in detail how all this happened.