Sahih Muslim Book 032, Hadith Number 6278.
Chapter : It is forbidden to curse the beasts.
Abu Burza al-Aslami reported that a slave-girl was riding a dromedary and there was also the luggage of people upon it, that she suddenly saw Allah's Apostle (may peace be upon him). The way of the mountain was narrow and she said (to that dromedary): Go ahead (but that dromedary did not move). She (that slave-girl), out of anger, said: O Allah, let that (dromedary) be damned. Thereupon Allah's Apostle (may peace be upon him) said: Let the dromedary on which the curse has been invoked not proceed with us.