A classical Egyptian report says that when Amr ibn al-As رضي الله عنه governed Egypt, local people told him of an old rite they believed necessary for the Nile’s annual rise: after twelve nights of the Coptic month of Ba'una, a virgin girl would be chosen, adorned with fine clothes and jewelry, and cast into the river. Amr rejected the rite. When the Nile then failed to rise as expected, he wrote to Umar ibn al-Khattab رضي الله عنه, who sent a card declaring that the river flows only by Allah’s command. The report says the card was placed in the Nile and the water rose dramatically. The surviving chain is weak and disconnected, so the event is presented as a classical reported karamah rather than certain history.
Amr ibn al-As رضي الله عنه rejected the practice and told them that Islam does not continue such customs. The people therefore abandoned it. According to the report, however, the Nile did not rise at the expected time, and the situation became serious enough that some people considered leaving the region because agriculture and ordinary life depended on the river.
Amr then wrote to the Caliph Umar ibn al-Khattab رضي الله عنه and informed him of what had happened. Umar replied that Amr had acted correctly in abolishing the old rite. He also sent a small written card to be placed in the Nile. The wording preserved in the report addresses the river directly: if the Nile flowed by its own power, then it should not flow; but if Allah, the One and the Overpowering, caused it to flow, then the appeal was to Allah to make it flow.
The report says that Amr placed the card in the Nile. By the next morning, the river had risen by sixteen cubits, and the people no longer returned to the former sacrificial custom. In the narrative, the central message is not the card as an independent power, but the rejection of a human-sacrifice rite and the affirmation that the river is under Allah’s command alone.
The report is preserved by Ibn Abd al-Hakam and also appears through the same basic transmission family in al-Lalaka'i and Abu al-Shaykh. Its surviving chain includes Ibn Lahi'ah, Qays ibn al-Hajjaj and an unnamed intermediary, so it is not a sound connected isnad. For that reason, the story should be presented respectfully as a well-known classical report attributed to Umar رضي الله عنه, while keeping its isnad limitation clear and avoiding modern measurements or scientific explanations not found in the source.
Conclusion
The report presents Umar رضي الله عنه and Amr ibn al-As رضي الله عنه as ending an old sacrificial rite associated with the Nile and affirming that the river flows only by Allah’s command. It is best published as a classical reported karamah with an explicit isnad caution.