Buraq:
Then he [Gabriel] brought the Buraq, handsome-faced and bridled, a tall, white beast, bigger than the donkey but smaller than the mule. He could place his hooves at the farthest boundary of his gaze. He had long ears. Whenever he faced a mountain his hind legs would extend, and whenever he went downhill his front legs would extend. He had two wings on his thighs which lent strength to his legs.
http://www.youtube.com/watch?v=16FdJrrAWSo