Is fasting on the day of Al-Israa’ wal-Mi'raaj obligatory, an innovation, or recommended?

Fasting includes that which is obligatory, like Ramadan (definition), and that which is less so, like fasting the days of Tasu'a and Ashura, the day of Arafah, three days from every month, and Mondays and Thursdays. As for the day of Isra and Mi'raj, its fasting is neither obligatory, nor recommended, nor Sunnah (definition), due to the lack of any evidence from the Prophet, peace and blessings be upon him, indicating that. Furthermore, the exact day of Isra and Mi'raj is disputed. Whoever fasts this day based on the belief that it is the Isra and Mi'raj commits an innovated bid'ah. However, if this day coincides with another Sunnah fast, such as a Monday or Thursday, or it coincides with a person's regular habit of fasting, then it is permissible to fast it for that reason, not because it is the day of Isra and Mi'raj.