What is the ruling on going to Hajj on the Day of Arafah and taking a plane at ten in the morning, without performing the rituals that precede the Day of Arafah? And is the Hajj invalidated if the plane arrives at Mount Arafah after Maghrib? And when must I be in Arafah for the Hajj to be valid?

There is no objection to entering into ihram (definition) for Hajj on the ninth day of Dhul-Hijjah and proceeding directly to Arafat. The Hajj is valid by entering Arafat between Dhuhr and the dawn of the tenth day, as this is the time for the standing (wuquf).

This is supported by the hadith (definition) of Urwah ibn Mudarris al-Ta'i, in which the Prophet, peace and blessings be upon him, said: "Whoever witnesses this prayer of ours, and stands with us until we depart, and has already stood at Arafat before that, whether at night or during the day, has completed his Hajj and fulfilled his obligations."

Scholars have agreed that the standing at Arafat extends until the dawn of the Day of Sacrifice (Yawm al-Nahr). As for its beginning, there is disagreement. The madhhab (definition) of Malik, Shafi'i, and the majority is that it begins from the decline of the sun on the Day of Arafat. Ahmad, however, said it begins from the dawn of the Day of Arafat.

The important thing is that whoever reaches Arafat at any point during this time, while being of sound mind, has completed his Hajj.