Abdullah bin Abbas reported,
A man may perform tawaf around the House while he remains in a state of ihlal until he enters the state of ihram for Hajj. When he rides out to Arafah, whoever can afford a sacrificial offering from camels, cattle, or sheep, whichever of these he wishes, may offer it. But if he cannot afford it, then he must fast three days during the Hajj, and that is before the day of Arafah. If the last of the three days falls on the day of Arafah, there is no harm in that.Then let him proceed until he stands at Arafat from the time of the Asr prayer until darkness falls. Then let them depart from Arafat, and when they have departed, let them continue until they reach Jam, where they spend the night. Then let him remember Allah much, and increase in takbir and tahlil before morning comes. Then proceed onward, for the people used to proceed, and Allah Most High said, "Then depart from the place from where all the people depart, and ask forgiveness of Allah. Indeed, Allah is Forgiving and Merciful" [Baqarah 2:199], until you cast the pebbles at the Jamrah.
Azami 5096
Sahihعن ابن عباس قال
يطوف الرجل بالبيت ما كان حلالا حتى يهل بالحج، فإذا ركب إلى عرفة فمن تيسر له هدية من الإبل أو البقر أو الغنم، ما تيسر له من ذلك، أي ذلك شاء، غير أنه إن لم يتيسر له فعليه ثلاثة أيام في الحج، وذلك قبل يوم عرفة، فإن كان آخر يوم من الأيام الثلاثة يوم عرفة فلا جناح عليه، ثم لينطلق حتى يقف بعرفات من صلاة العصر إلى أن يكون الظلام، ثم ليدفعوا من عرفات إذا أفاضوا منها حتى يبلغوا جمعا الذي يبيتون به، ثم ليذكر الله كثيرا، وأكثروا التكبير والتهليل قبل أن تصبحوا، ثم أفيضوا فإن الناس كانوا يفيضون، وقال الله تعالى: {ثم أفيضوا من حيث أفاض الناس واستغفروا الله إن الله غفور رحيم} [البقرة: ١٩٩] حتى ترموا الجمرة.
Bukhari related it in the tafsir (4521) from Muhammad bin Abu Bakr, who said, Fudayl bin Sulayman narrated to us, who said, Musa bin Uqba narrated to us, who said, Kurayb informed me, from Ibn Abbas, and he mentioned it.As for the saying of Allah Most High, "Then depart from where the people depart" [Baqarah 2:199], the apparent sense of the verse's wording is that this refers to the departure from Muzdalifa, because it is mentioned with the word "then" following the command to remember Allah at the sacred site. Some commentators answered this by saying that the command to remember Allah at the sacred site comes after the departure from Arafat, which was mentioned in the form of a statement of fact regarding what had already occurred concerning the place from which the departure is prescribed. So the meaning would be, when you depart, remember Allah, then let your departure be from where the people depart, not from where the Hums used to depart. Or the meaning could be, when you depart from Arafat to the sacred site, remember Allah there, and let your departure be from the place from which the people other than the Hums depart.Tahawi preferred the view that "then" here carries the meaning of "and," and is not meant to indicate sequence, so its meaning is for emphasis rather than for strict ordering. The meaning would then be, when you depart from Arafat, remember Allah at the sacred site, then make your departure the one from which the people depart, meaning from Arafat, not from the place you used to depart from in the pre-Islamic era, which was Muzdalifa. Other views have also been given. See Fath al-Bari.As for the departure from Arafat, and the fact that Hajj is not complete except by departing from it, the preceding verse suffices for this, namely the saying of Allah Most High, "So when you depart from Arafat, remember Allah at the sacred site" [Surah Baqarah 2:198]. However, taking the verse according to its apparent sense does not align with the sahih hadiths reported on this matter, and Allah Most High knows best.Among the commentators there are those who held to the apparent sense of the verse, saying that the command to depart in the verse means that the departure referred to here is from Muzdalifa, where the people depart, meaning as a general category, whether they were in the pre-Islamic era since the time of Ibrahim 
or in Islam after Hajj was legislated.