Musnad Ahmad 670:0

Narrated by Abd al-Rahman ibn Ya'mar: A man came to the Prophet (ﷺ) and asked him about the Hajj. The Prophet (ﷺ) said: "Hajj is Arafah." Whoever reaches the night of Arafah before the break of dawn, he has attained the Hajj. The days of Mina are three; whoever hastens in two days, there is no sin upon him, and whoever delays, there is no sin upon him. Then he made a man ride behind him and he began to proclaim among the people: "Hajj is Arafah. Whoever reaches the night of Arafah before the break of dawn, he has attained the Hajj. The days of Mina are three; whoever hastens in two days, there is no sin upon him, and whoever delays, there is no sin upon him."