Christianity and Islam are to very closely related religions, and they share the same origins, and some of the same history. The Koran and the Old Testament of the Bible are very closely related, in that many of the stories share the same points and characters. One of the overlapping stories is the story of the Flood. Although the main point or objective of the story is the same the means that each book gets there by is very different. Although in both Koran and in the Bible, Noah is the messenger to God, he plays opposing roles in each of the stories. The outcome of both though is the same. In the Bible, God speaks to Noah, saying many times over that the world that he created has become corrupt. The men and women that he had created were filled with "wickedness". For this reason he wanted to destroy all that he had created, anything that was living he wanted dead, may that be men, women, animals, or plants; he wanted nothing left alive. There was only one person that God felt merited his life, and that person was Noah. God felt that the best way to rid the earth of all creation would be to have it rain for as long as it took to submerge the earth. Once He had decided this, He told Noah to build an ark, an ark that would be large enough to house his family and many different species of animals. God also explained to Noah how the ark should be built, and that after the ark had been built, Noah should go out and seek between two and seven of each kind, being sure to have collected at least one male, and one female, the number dependent on whether the animal was "clean" or not. God also, instructed Noah to make sure that there was enough food on the ark for himself, his family, and the animals to survive the long "journey". Noah did all these things, once he had completed his assigned tasks, God carried out His plan.
After either seven days, or forty days, it is unclear which one, the rain ceased.