What is the importance the plain of Arafat in Hajj?

Arafat is a plain about 20 km (12 mi) southeast of Mecca. It is the place where Arafat wuquf takes place. When Allah removed Adam and Eve from paradise and made them dwell on the earth, they met in the plain of Arafat.  Adam turned to Allah and made dua to repentance and Allah forgave him in the Jabal Rahmah. Therefore, people called the place Jabal Rahmah which means a hill of Rahman. According to Islamic tradition, Jabal Rahma is the place where the Prophet Muhammad (peace be upon him) stood and delivered the Farewell Sermon to the Muslims who had accompanied him for the Hajj towards the end of his life. 

The Prophet (peace be upon him) said: “All Arafat area is the wuquf place. The plain of Mina is the place where an animal needs to be sacrificed. “ Wuquf means existing in the plain of Arafat. All pilgrims must be in the plain of Arafat from Zuhr to Magrib to perform wuquf on the day of Arafat. 

Allah says in the Quran (interpretation of the meaning): There is no blame upon you for seeking bounty from your Lord [during Hajj]. But when you depart from 'Arafat, remember Allah at al- Mash'ar al-Haram. And remember Him, as He has guided you, for indeed, you were before that among those astray. (Surah Al- Baqarah:198)

People do not accept as Hujjaj those who do not stand or pass through the plain of Arafat on the day of Arafat.