How authentic is the Hadith: "O Allah, I am innocent of what Khalid did"?

Al-Bukhari narrated that the Prophet (peace and blessings be upon him) sent Khalid ibn al-Walid to Banu Jadhimah. Khalid invited them to Islam, and they said, "Saba'na, saba'na" (meaning, "We have apostatized," as they did not articulate "We have embraced Islam" correctly). Khalid then began to kill and take captives from them, even ordering the killing of the captives. However, Ibn Umar and those with him refused to kill their captives. When they returned to the Prophet (peace and blessings be upon him), he said, "O Allah, I disavow myself before You of what Khalid has done," twice. Al-Bukhari titled a chapter on rejecting the ijtihad (independent reasoning) of an Imam if it contradicts the truth. Ibn Hajar mentioned that Khalid was sent as a caller (to Islam), not a fighter, and that Ibn Umar understood that they intended Islam, while Khalid resented their deviation from the precise wording of Islam, so he killed them based on his interpretation. The Prophet (peace and blessings be upon him) rebuked Khalid for his haste and lack of verification, and sent Ali to pay the blood money for those killed. The Prophet (peace and blessings be upon him) did not punish Khalid for his ijtihad, but he disavowed his action to teach people that he had not authorized it.