It was said to Umar bin Khattab, "Would you not appoint a successor, Commander of the Faithful?"He replied, "Had Abu Ubayda bin Jarra been alive, I would have appointed him. Then, when I came before my Lord and He asked me, 'Why did you appoint him as successor over the nation of Muhammad?' I would say, 'I heard Your servant and beloved say, Every nation has a trustee, and the trustee of this nation is Abu Ubayda bin Jarra.' And had Khalid bin Walid been alive, I would have appointed him. Then, when I came before my Lord and He asked me, 'Whom did you appoint as successor over the nation of Muhammad?' I would say, 'I heard Your servant and beloved say of Khalid, He is a sword among the swords of Allah, which Allah has unsheathed against the polytheists.'"
قيل لعمر بن الخطاب: لو عهدت يا أمير المؤمنين؟ قال: لو أدركت أبا عبيدة بن الجراح ثم وليته، ثم قدمت على ربي، فقال لي: لم استخلفته على أمة محمد؟ قلت: سمعت عبدك وخليلك يقول: لكل أمة أمين، وإن أمين هذه الأمة أبو عبيدة بن الجراح، ولو أدركت خالد بن الوليد ثم وليته، ثم قدمت على ربي، فقال لي: من استخلفت على أمة محمد؟ لقلت: سمعت عبدك وخليلك يقول لخالد: سيف من سيوف الله سله الله على المشركين.
Ibn Abu Asim narrated it in al-Ahad wal-Mathani (697) and Shashi in his Musnad (617) - and the wording here follows his version - both of them through the route of Damra bin Rabia, from Yahya bin Abu Amr Shaybani, from Abu Ajfa, who related it.Abu Ajfa is Sulami Basri. It has been said that his name was Harim bin Nasib, and it has also been said the opposite. He is a disputed narrator. Ibn Main and Daraqutni deemed him reliable, and Ibn Hibban mentioned him among the trustworthy narrators. Bukhari said, "There is something questionable in his hadith." Abu Ahmad Hakim said, "His hadith is not well established." Yaqub Fasawi said, "Abu Ajfa is unknown, no one knows who he is," and he judged this hadith to be baseless. al-Marifa wal-Tarikh (2/437-438).That is what he said, but I do not know the basis for judging this hadith baseless. As for Abu Ajfa, it has already been established that he is a disputed narrator, so if someone were to go with grading him hasan, he would not have strayed from the correct view.