If Abu Bakr was the dearest of people to the Prophet, why did he say: "Had there been a prophet after me, it would have been Umar"? And is this hadith authentic?

First: The hadith is weak due to the weakness of its narrator, Musharrih ibn Ha'an, who narrates objectionable traditions for which he is not followed. Imam Ahmad said of him, "Discard him; for in my view, he narrates objectionable traditions."

Second: Assuming the authenticity of the hadith, scholars have differed in its interpretation: 1. It is from the knowledge of the unseen, and if it were destined for a prophet to exist after the Prophet (peace be upon him), it would have been Umar, and Allah would have prepared for him the means of prophecy. 2. It is to inform that prophethood is a choice from Allah and not by merit. Umar (may Allah be pleased with him) possessed many of the qualities and characteristics of prophets. So, if qualities were to necessitate prophethood, then Umar would have been a messenger. This indicates that the apparent qualities of prophets to people are truthfulness to Allah and trust in Him, and turning away from what is less than Him. These qualities were found in Abu Bakr more than in Umar. However, the Prophet specifically mentioned Umar to show that prophethood is by divine will, not by causes. 3. Umar was specifically mentioned due to the frequent agreement of his statements with what was later revealed in the Quran. Thus, he was close to prophethood by his closeness to the Quran. This does not mean that he is superior to Abu Bakr; rather, Abu Bakr is the best of the Ummah by the consensus of the Ahl al-Sunnah.