SB 10.15.48
atha gavas ca gopas ca
nidaghatapa-piditah
dustam jalam papus tasyas
trsnarta visa-dusitam
Translation:
At that time the cows and cowherd boys were feeling acute distress from the glaring summer sun. Afflicted by thirst, they drank the water of the Yamuna River. But it had been contaminated with poison.