There is consensus among Muslim scholars that spending the day at `Arafah is the most important part of Hajj. The Prophet (peace and blessings be upon him) ordered an announcer to proclaim, “Hajj is (spending the day at) `Arafah, so he who joins other pilgrims on the night of Muzdalifah before dawn will be considered as having performed Hajj.”
It is Sunnah to leave `Arafah peacefully and calmly after sunset. It is also desirable to utter Talbiyah and make remembrance of Allah while leaving `Arafah.
In this regard, we cite what Sheikh Sayyed Sabiq states in his well-known book Fiqh As-Sunnah:
According to the Sunnah, pilgrims should leave `Arafah quietly and peacefully after sunset. The Prophet (peace and blessings be upon him) left `Arafah very peacefully and quietly, holding the reins of his she-camel tightly, while he said to the people, “O people, walk calmly; rushing or making haste is not a virtue” (Al-Bukhari and Muslim). They also reported that the Prophet (peace and blessings be upon him) let his she-camel go at a normal pace, but when he found ample space in front of him he urged it to go faster.” He did this out of compassion and consideration for the people.
It is desirable for pilgrims to utter Talbiyah and make remembrance of Allah as much as possible. The Prophet (peace and blessings be upon him) continued to repeat Talbiyah until he threw the pebbles at JamratAl-`Aqabah. Ash`ath ibn Sulaim reported from his father that he said, “I went with Ibn `Umar from `Arafah to Muzdalifah. He did not stop making remembrance of Allah and declaring His Oneness until we reached Muzdalifah” (Abu Dawud).
Allah Almighty knows best.