Intelligence Bureau of Muslims
By: Ayatullah Ja'far Subhani
From the day the Prophet had settled down in Madina he always sent clever persons to different sides, so that they might inform him about the conditions prevailing in those areas as well as the activities of people residing outside the territories of Islam. The informants reported that a strong military alliance had been formed against Islam and those people would march on an appointed day to besiege Madina. The Prophet immediately formed a consultative council so that they might take decisions keeping in view the bitter experiences gained from the Battle of Uhud. Some persons preferred fortified defence from the towers and the high places instead of going out of the city to face the enemy. However, this scheme was not adequate, because the huge pack of warriors of Arabia with thousands of soldiers could destroy the fortresses and the towers and could overpower the Muslims. It was, therefore, necessary to take steps to ensure that the enemy did not succeed in approaching Madina.
Salman Farsi, who was fully conversant with the art of Iranian warfare, said: "In Persia, as and when people are threatened with an attack by the enemies, they dig a deep ditch around the town and thus check their advance. Hence, it would be appropriate to safeguard the vulnerable points of Madina by means of a ditch and thus to hold back the enemy in those areas. Simultaneously, towers and sentry posts should be constructed by the bank of the ditch for purposes of defence and the enemies should be prevented from crossing the ditch by shooting arrows and hurling stones on them from the towers and the fortresses".
The suggestion made by Salman was accepted unanimously and this defensive scheme contributed a good deal towards the safety of the Muslims accompanied by some persons, personally inspected the vulnerable points and marked out the spots where the ditch was to be dug. It was decided that the ditch should be dug from Uhud up to Ratij and, in order to maintain a good order, every forty cubits were entrusted to ten men. The Prophet himself struck the first pick on the ground and began digging the earth when Ali busied himself with throwing the clay out. The face and forehead of the Prophet was perspiring and he was uttering, "Real life is the life of the Hereafter. O Allah! Forgive the Muhajirs and the Ansar!"
By engaging himself in this work the Prophet manifested a part of the programme of Islam and made the Muslim society understand that a commander of the army and a leader of the society should endure hardships like others and should alleviate their burden. The Prophet's labour created a peculiar enthusiasm amongst the Muslims and all of them, without any exception, started work, so much so that the Jews belonging to the tribe of Bani Qurayzah who had concluded a pact with the Muslims also rendered help by providing implements. The Muslims were very hard up in those days for provisions, and the well-off families were rendering help to the soldiers of Islam.
When the digging of the ditch became difficult on account of the appearance of big stones they approached the Prophet, who himself broke the big rocks with a strong blow.
The length of the ditch can be estimated by taking into account the number of workers. According to a popular version the number of the Muslims in those days was 3000, and if digging of 40 cubits was performed by ten persons the length of the ditch would come to 12,000 cubits and its breadth was so much that clever and experienced riders could not cross it on horseback.
THE WELL-KNOWN REMARKS OF THE PROPHET ABOUT SALMAN
When the workers were being distributed a dispute cropped up between the Muhajirs and the Ansar with regard to Salman. Each of the two parties claimed that Salman belonged to them and should work along with them. At this juncture the Prophet put an end to the dispute with a decisive order and said: "Salman is one of the members of my household".
The Prophet spent his days and nights by the bank of the ditch till the work was completed. However, the hypocrites failed to do the work on various excuses and at times went away to their houses without obtaining permission from the Prophet, while the true believers remained busy in their work with firm determination, and discontinued work on good excuse after obtaining permission from the commander, and returned to work again when the excuse ceased to exist. This matter has been narrated in the 62nd and 63rd verses of Surah al-Nur.
 Tarikh-i Tabari, vol. II, page 224.
 Mughazi-i Waqidi, vol. II, page 445.
 Seerah-i Ibn Hisham, vol. II, p. 220; Mughazi, vol. II, p. 453.