Is fasting the Day of Arafah without breaking the fast at Maghrib and continuing the fast until the Day of Eid, then breaking it with the liver of the sacrificial animal, considered a Sunnah, an innovation, or a misunderstanding of the Sunnah? And did the Prophet, peace and blessings be upon him, break his fast on the Day of Arafah at Maghrib, with the first thing entering his stomach on the Day of Eid being from the sacrificial animal, or did he continue his fast from the Day of Arafah until he broke it with the sacrificial animal?

Intentionally delaying breaking the fast after sunset is makrooh (disliked) and an innovation (bid'ah). The Sunnah for one who is fasting is to hasten breaking their fast, due to the Prophet's (peace be upon him) saying: "People will remain in goodness as long as they hasten the breaking of the fast." As for the morning of 'Eid al-Adha (the Day of Sacrifice), the Sunnah is not to eat until the sacrificer returns from the prayer and eats from his sacrificial animal. It is not prescribed for someone who fasted on the Day of 'Arafah to continue his fast until he breaks it with his sacrificial animal; rather, he should hasten his breaking of the fast, then not eat anything after the morning until he returns from the prayer ground and eats from his sacrificial animal. As for specifically eating from the liver, there is a hadith about it that Al-Albani graded as weak.