Srimad Bhagavatam Canto 10, Chapter 21, Text 14

SB 10.21.14

prayo batamba vihaga munayo vane ’smin
 krsneksitam tad-uditam kala-venu-gitam
aruhya ye druma-bhujan rucira-pravalan
 srnvanti milita-drso vigatanya-vacah
O mother, in this forest all the birds have risen onto the beautiful branches of the trees to see Krsna. With closed eyes they are simply listening in silence to the sweet vibrations of His flute, and they are not attracted by any other sound. Surely these birds are on the same level as great sages.
The birds resemble sages because they live in the forest, keep their eyes closed, observe silence and remain motionless. Significantly, it is stated here that even great sages become maddened by the sound of Krsna’s flute, which is a completely spiritual vibration.
The word rucira-pravalan indicates that even the branches of the trees are transformed in ecstasy when struck by the vibration of Krsna’s flute-song. Indra, Brahma, Siva and Visnu, being primordial gods, travel throughout the universe and have extensive knowledge of the science of music, and yet even these great personalities have never heard or composed music like that which emanates from Krsna’s flute. Indeed, the birds are so moved by the blissful sound that in their ecstasy they close their eyes and cling to the branches to avoid falling off the trees.
Srila Visvanatha Cakravarti Thakura explains that the gopis would sometimes address each other as amba, “mother.”
Srimad Bhagavatam Canto 10, Chapter 21, Text 13
Srimad Bhagavatam Canto 10, Chapter 21, Text 15