We begin the story of the life of Muhammad صل الله عليه و سلم with the story of the zamzam well. As many Muslims are familiar with, the Well of Zamzam was a blessing for the sake of Ismail عليه السلام. When the Lady Hajra had run out of milk in the middle of the barren and empty desert, she implored Allah for sustenance. A gushing outpouring of water appeared under the kicking feet of Ismail عليه السلام, and had Sayyidina Hajra not tried to contain it, it would likely have turned into a large river to flow through Makkah. As it happens, she held her hands up the flowing water, and cried “zam zam!” in a surprised attempt to stop it’s flow, and then proceeded to build up a mound of sand to form a wall around it. Thus, it was contained to a well, and did not become that river.
At the time, there were two tribes prevalent around Makkah, the Jurhum and Khuza’ah. Sayyidina Hajra permitted the tribes to take water from the well of Zam Zam, but insisted on maintaining rights to the well (a testimony to her mental fortitude–as a woman on her own in the desert, she was certainly strong to be able to negotiate with two tribes that were generally at war with each other, and would have certainly had no qualms about warring with her). Eventually, a time came when the Jurhum tribe was driven out of Makkah by the Khuza’ah. On their way out, the tribe decided to cover up the well, perhaps feeling spiteful towards the Khuza’ah and wanting them to suffer a bit. For a long time thereafter, the well of Zam Zam was no longer visible, and while the general location was know, the specific location was elusive.
Eventually, Abdul Muttalib, the grandfather of Muhammad صل الله عليه و سلم, was given the task of providing pilgrims to Makkah with water. Thus began his search for the well of Zam Zam. One night, he saw a dream telling him where the well was located, and he began digging the next day at that spot. The rest of the Quraish resented this, because all this digging happened to be at the spot at which two of their idols (Isaf and Nailah) were standing. Abdul Muttalib continued to dig with his son, and realizing the extent of his isolation (just two of them against a whole tribe), he asked Allah to give him ten sons, and if Allah granted him his wish, he’d sacrifice one of them in the name of Allah. A short time later, the well was discovered, and over the course of his life, Abdul Muttalib was also granted the ten sons he’d asked for.
The time came when he had to fulfill his oath to sacrifice one of those sons. He went to the Ka’bah and decided to draw lots to determine which son it would be. The arrows of chance chose Abdullah, the son who was most dear to Abdul Muttalib, and they left for the altar of sacrifice. His family and the various chiefs of the Quraish tried mightily to stop this sacrifice, but Abdul Muttalib was intent on fulfilling his promise to Allah. Ultimately, they all convinced him to take the advice of one of their prominent soothsayers, Saja, who would be able to find a wise solution. Abdul Muttalib agreed to this idea, as I can imagine he was not all too eager to see the demise of his son.
The soothsayer advised that the blood money for a single person was ten camels. So, they should put Abdullah on one side, ten camels on the other side, and then draw lots. If the camels were chosen, then they would be slaughtered; but if Abdullah was chosen, then ten more camels should be added and lots should be once again be drawn. This process should continue for as long as it takes for the arrows of chance to fall upon the camels. In the end, ten lots were drawn, for the eventual number of 100 camels. Since then, the blood money for one person killed has been fixed at 100 camels. (In short, killing a human being is expensive business. Contrary to popular opinion, camels in good health are not cheap. A hundred of them, forget about it.)