There was a time when Egypt was conquered by Muslims, Caliph Umar Al-Khattab put Amru Al-Ash as the governor of that new Muslim territory. Amru Al-Ash was famous as a valiant commander and an efficient and wise administrator.
After some period, the month of Bowana (June) came. At the beginning of the month a delegation of the “Qabti” tribe met the governor and said that one habit of the river Nile is such that if not fulfilled it (the Nile) stops flowing.
The governor asked. “What’s that?”.
They said: “After 12 nights of this month Bowana (June) has passed, we grab a beautiful young girl, persuade her parents, decorate this young girl with good clothes and jewelry and put her in the river Nile. After that the river flows with full force”
The governor said: “In Islam such things do never happen. Islam has destroyed all the illiterate customs and superstitions of the past and is free of all such things.”
Hearing this the delegation left. But what really happened was what the delegation had said. After 12 nights the river Nile really stopped flowing as this culture was not followed by the tribe and the river Nile dried out and the following three months Bowana (June), Abeeb (July) and Masri (August) passed like that. Such was the state that the tribes started moving to other places where they could find water
Time flew by and the river truly drying up as was foretold. Since farming in Egypt really depended on the river, the Egyptians started to panic and moved to other new verdant land.
That situation forced Amru to write upon Caliph Umar in Medina for his opinion. Amru himself felt terrible on how to solve the problem. Then, Caliph Umar replied his answer in a letter.
The Caliph said: “You did the right thing, and said the truth, that Islam demolishes all the illiterate culture of the past. I am sending along a letter, which you put it in the river Nile.”
The Governor read the letter and it wrote:
“This letter is sent to the river of Nile by Umar, servant of Allah and Commander of the Believers. O river of Nile, if the water is flowed on your will, behold that we do not need it. But if it flows in the will of Allah, thus, we pray to Him to let flow the water in the river.”
After the letter was thrown into the river, the river was filled with water up to forty-eight feet deep in the same night. Since then, the pagan ceremony for the river has been disappeared.
Source : http://www.ikhwan-insight.com