A classical report says that during a severe drought in the time of Umar ibn al-Khattab may Allah be pleased with him, Umar led a prayer for rain, turned his cloak, asked Allah for forgiveness and rain, and rain fell before the people left. The same weak report says that Bedouins later arrived and described hearing a voice from a cloud saying that relief had come to Abu Hafs. Authentic hadith independently confirms communal istisqa under Umar and the Prophetic practice of two rak'ahs and turning the cloak, but it does not authenticate this exact cloud-voice episode.
The same report then adds its most extraordinary detail. It says that Bedouins came to Umar and told him that a cloud had shaded them. They reported hearing a voice from the cloud saying that relief had come to Abu Hafs, the well-known kunya of Umar, and that the statement was repeated twice. In the classical presentation, the arrival of rain and this reported voice form the central extraordinary sequence associated with Umar.
The earliest checked preservation of this account is in works of Ibn Abi al-Dunya. He records the event in Mujabu al-Da'wa and also in al-Hawatif. Al-Lalaka'i later includes the same report in his chapter on the karamat of Umar, and Ibn Kathir reproduces it in his historical account of the drought years. These later appearances, however, do not provide independent confirmation of the extraordinary detail, because they depend on the same core transmission route.
That route has serious weaknesses. It passes through 'Ata ibn Muslim al-Khaffaf from Abdullah ibn Umar ibn Hafs al-Umari from Khawwat ibn Jubayr. Abdullah al-Umari was judged weak, and the route is disconnected because he did not meet Khawwat. 'Ata ibn Muslim also received substantial criticism for mistakes and weak memory. A later scholarly note on the same cloud-voice report likewise labels its chain weak.
There is, however, a stronger historical background that must be kept separate. Sahih al-Bukhari authentically reports that Umar conducted communal istisqa during drought and that rain followed when he sought rain through al-Abbas. Other sahih Bukhari reports establish that the Prophet peace and blessings be upon him performed istisqa with two rak'ahs and turned his cloak. These authentic reports support the general setting of drought, prayer for rain, rainfall, and the ritual form, but they do not prove that they describe this same event or authenticate the cloud-voice detail.
The most careful conclusion is therefore that Sunni classical sources preserve a report of rain after Umar's istisqa together with a striking voice-from-a-cloud account. The story has a genuine classical reception, but the exact extraordinary detail rests on a weak and disconnected chain and should be presented as a reported karamah rather than as an established sahih event.
Conclusion
Classical Sunni sources preserve a report that rain followed Umar ibn al-Khattab’s istisqa and that Bedouins then related a voice from a cloud announcing relief to Abu Hafs. Because the exact extraordinary report has a weak and disconnected chain, it is best presented as a low-confidence reported karamah, not as an authenticated historical certainty.