The Messenger of Allah ﷺ said, "O Allah, strengthen Islam through Umar bin Khattab in particular."
قال رسول الله ﷺ: اللهم أعز الإسلام بعمر بن الخطاب خاصة.
Ibn Majah narrated it (105), and Hakim graded it sahih (3/83), and Bayhaqi narrated it through his route in Kubra (6/370), both of them through various routes from Hisham bin Urwa, from his father, from Ayesha, as I mentioned. Its chain is sahih. Ibn Hajar also graded it sahih in Fath al-Bari (48/7).On this subject there is also a report from Ibn Abbas that the Prophet ﷺ said, "O Allah, strengthen Islam through Abu Jahl bin Hisham or through Umar bin Khattab." He said, so the next morning Umar went to the Messenger of Allah ﷺ and accepted Islam. Tirmidhi narrated it (3683) from Abu Kurayb, who said, Yunus bin Bukayr narrated to us, from Nadr Abu Umar, from Ikrima, from Ibn Abbas, as I mentioned. He said, "This is a gharib hadith from this route, and some scholars have criticized Nadr Abu Umar, for he narrates unusual reports."This is as he said, for Nadr bin Abdul-Rahman Abu Umar Khazzaz is daif by the agreement of the scholars, and Bukhari attributed its weakness to him, as mentioned in Ilal Tirmidhi Kabir (2/936).Hakim also narrated it (3/38) through the route of Saeed bin Sulayman (who is Wasiti), who said, Mubarak bin Fadala narrated to us, from Ubaydullah bin Umar, from Nafi, from Ibn Umar, from Ibn Abbas, from the Prophet ﷺ, that he said, "O Allah, strengthen Islam through Umar." But the correct view is that this belongs to the musnad of Ibn Umar, not to the musnad of Ibn Abbas, as already mentioned.