Why did the Prophet, peace and blessings be upon him, say: "If there were to be a prophet after me, it would have been Umar," and not say: "It would have been Abu Bakr," even though Abu Bakr is superior to Umar?

Scholars have differed on the authenticity of the hadith (definition) "Had there been a prophet after me, it would have been Umar." Some, like Al-Hakim, Al-Dhahabi, and Al-Tirmidhi, authenticated it, while others, like Imam Ahmad, considered it weak. Assuming its authenticity, scholars have offered various explanations for singling out Umar for mention rather than Abu Bakr. Among these explanations are: Umar's opinions frequently concurred with the Quran, and his closeness to prophethood due to his closeness to the Quran, yet there is no prophet after Muhammad, peace be upon him. Ibn Taymiyyah clarified that the truthful (Siddiq) Abu Bakr was more complete than Umar because the Siddiq receives from the infallible Prophet, whereas the inspired (Muhaddath) Umar receives from the inspiration of his own fallible heart and then verifies it against the Quran and Sunnah (definition).