I came to the Prophet ﷺ while he was at Arafah. A group of people from the people of Najd arrived and instructed one of their men, who called out, "Messenger of Allah, how is the Hajj performed?"The Messenger of Allah ﷺ then ordered a man to call out, "The Hajj, the Hajj is the day of Arafah. Whoever arrives before the dawn prayer on the night of Jam has completed his Hajj. The days of Mina are three. Whoever hastens to leave in two days, there is no sin upon him, and whoever delays, there is no sin upon him."He then mounted a man behind him on his ride, and that man went about announcing this.
حدثنا محمد بن كثير حدثنا سفيان حدثني بكير بن عطاء
أتيت النبي ﷺ وهو بعرفة فجاء ناس أو نفر من أهل نجد فأمروا رجلا فنادى رسول الله ﷺ كيف الحج فأمر رسول الله ﷺ رجلا فنادى الحج الحج يوم عرفة من جاء قبل صلاة الصبح من ليلة جمع فتم حجه أيام منى ثلاثة فمن تعجل في يومين فلا إثم عليه ومن تأخر فلا إثم عليه قال ثم أردف رجلا خلفه فجعل ينادي بذلك
Its isnad is sahih. Tirmidhi reported it in the book of Hajj, chapter on what has been said about one who catches up with the imam catching up with Hajj, hadith no. 889, 890, as did Nasai, hadith no. 3019, and Ibn Majah, hadith no. 3015, from the hadith of Sufyan Thawri through this same route. Ibn Khuzayma graded it sahih, hadith no. 2823, as did Hakim, 1/2/278, 463, 464, and Dhahabi agreed with him.