Khufu's Curse is a side quest in Egypt (Act II). It is given by Tekenu, a nomad standing next to the entrance to the Tomb of Khufu in the Giza Plateau. He will tell you about monsters having broken into the pyramid, seeking to defile the Pharaoh's Sarcophagus to unleash a deadly plague.
Enter the Pyramid of Khufu and proceed up the ramp until you get to a large Ornamented Stone Door (there are actually three, it's the one in the center). Proceed further to find a Jackalman hero named Sadiki, Champion of Anubis. He is guarded by several Jackalman Beserkers, but he shouldn't be too hard to defeat. Killing him completes the quest.
Opening the Pharaonic Sarcophagus will just set off a poison trap, but nothing else will happen. Tekenu, the nomad who gave you this quest, will disappear after completing the quest.
Reward: 12500 Experience