It is said that the ancient Egyptians were having some rituals regarding the Nile and irrigation. when the Nile was late in flooding they used to choose a girl with beauty and social status and they pay and compensate her father well. They prepare her and then they throw her in the Nile as a sacrifice and the call her the bride of the Nile. They believed that doing this the Nile will be satisfied and will flood the water for their thirsty land fields.
When the Muslims cam to Egypt 1400 years ago they learned about this ritual and the Muslim ruler in that time Amr Bin El As was not ready to allow such rituals that conflicts with the Islamic teachings but on the other hand the people of Egypt believe in it and the river is becoming late and the plants will die. Carried by his confusion he send a letter to the Khalif of the Muslims in Medina asking him what to do. The Khalif answered with a letter and told the messenger to tell Amr to throw that letter in the Nile. That letter reads as the following.
“Oh river of Egypt. If you would overflow out of your own will and choice then we have nothing to do with you. But if you overflow by the command of Allah then we ask Allah to make you overflow.”
The next day the river flooded and fields were saved and since then the Egyptians learnt that everything runs in this universe by the command of Allah and they never offered again a bride for the Nile.