The Arafah sermon is one of the most symbolically important events of the Haji, connecting modern jamaah haji to Nabi Muhammad's (shallallahu alaihi wa sallam) Farewell Sermon (Khutbat al-Wada') delivered in the same location in 10 AH (632 CE). In that historic address, Nabi proclaimed the equality of all humans regardless of race, the sanctity of life and property, the abolition of pre-Islamic injustices, the rights of women, and the importance of holding fast to Al-Al-Quran and Sunnah. He concluded by asking the gathering to bear witness that he had conveyed the message.
Today, the Haji sermon is delivered at Masjid al-Namirah by a senior Saudi scholar appointed by the government. It is given after the sun passes its zenith on the 9th of Dzulhijjah, before the combined Dhuhr-Asr shalat. The sermon typically addresses contemporary Muslim concerns while echoing the timeless themes of the Farewell Sermon. It is broadcast via loudspeakers across the entire Arafah plain and televised globally.
While the sermon is a Sunnah and attending it is sunnah, jamaah haji should note that the actual pillar (rukun) of Haji is the wuquf — standing anywhere within the boundaries of Arafah during the designated time period. A jamaah haji who misses the sermon but stands at Arafah has fulfilled the pillar. Conversely, someone who attends the sermon in the front portion of Masjid al-Namirah (which is technically in Uranah, outside Arafah boundaries) must ensure they move into Arafah proper after the shalat.