What is the interpretation of the Prophet's fasting on the ninth day of Dhul-Hijjah, even though it is the Day of Arafah, and did he fast it while not in a state of Ihram, or was this one of his unique prerogatives?

The texts indicate that the Prophet, peace and blessings be upon him, fasted on the Day of 'Arafah, but this is understood to mean that he was not in a state of ihram (ritual consecration for Hajj). What is established in the two Sahih collections is that he was not fasting on the Day of 'Arafah. Al-Nasa'i narrated from Abdullah ibn 'Umar that he performed Hajj with the Prophet, peace and blessings be upon him, and with the Rightly Guided Caliphs, and they did not fast on the Day of 'Arafah. He (Ibn 'Umar) himself would not fast it, nor would he command or forbid it. Al-Hafiz mentioned in Al-Fath that the majority of scholars recommend that the pilgrim not fast on the Day of 'Arafah.