using trenches from the Persians, possibly via the Ghassanid Arabs who saw their king killed at the Battle of Thannuris in 527 by this tactic. The adopting is reflected in the Arabic word for this battle, khandaq (), which is a borrowing via Aramaic from Pahlavi kandak. Siege of Medina The siege of Medina began in January 627 and lasted for 20 nights. Adding in the six days of trench-building, the entire operation lasted 27 days and was contained within a single month (5 Shawwal-1 Dhu al-Qi'dah). Since sieges were uncommon in Arabian warfare, the arriving Confederates were unprepared to deal with the trenches dug by the Muslims. The Confederates tried to attack with horsemen in hopes of forcing a passage, but the Medinans were rigidly entrenched, preventing such a crossing. Both of the armies gathered on either side of the trench and spent two or three weeks exchanging insults in prose and verse, backed up with arrows fired from a comfortable distance. According to Rodinson, there were three dead among the attackers and five among the defenders. On the other hand, the harvest had been gathered and the besiegers had some trouble finding food for their horses, which proved of no use to them in the attack. The Quraysh veterans grew impatient with the deadlock. A group of militants led by ‘Amr ibn ‘Abd Wudd (who was thought to be equal to a thousand men in fighting) and Ikrimah ibn Abi Jahl attempted to thrust through the trench and managed to effect a crossing, occupying a marshy area near the hillock of Sala. 'Amr challenged the Muslims to a duel. According to Shia sources, in response, Ali ibn Abi Talib accepted the challenge, and was sent by Muhammad to fight. As Ali went to fight Amr ibn Abd Wudd, Muhammad said about Ali, "He is the embodiment of all Faith who is going to an encounter with the embodiment of all Unbelief." Both the fighters got lost in the dust as the duel became intense. Finally, the soldiers heard screams which hinted at decisive blows, but it was unclear which of the two was successful. The slogan, 'Allahu Akbar' (God is the greatest) from the dust confirmed Ali's victory. The Confederates were forced to withdraw in a state of panic and confusion. According to Shia sources, Ali allowed Amr's entourage to retreat; Ali never pursued a fleeing enemy. The