The she-donkey saw the angel of the L-rd, and it crouched down under Balaam. Balaam’s anger flared, and he beat the she-donkey with a stick. The L-rd opened the mouth of the she-donkey, and she said to Balaam, “What have I done to you that you have struck me these three times?” (22:27-8)
Balak, the king of Moab, hired Balaam to curse the people of Israel. On the way, Balaam is thrown off course by his donkey, who sees the angel G d sent to block their way. In the painting, the donkey seems to be falling over as it crouches down under Balaam. Dressed in purple, the color of royalty, the haughty soothsayer, falls down to the level of his animal. The Kli Yakar explains that this was to impress upon Balaam that there is no place for pride. Even though he was given the
Article source: http://www.chabad.org/parshah/article_cdo/aid/2994603/jewish/Balaams-Donkey.htm