Quraysh and those who followed their religion used to stand at Muzdalifa, and they were called the Hums. The rest of the Arabs would stand at Arafat. When Islam came, Allah commanded His Prophet ﷺ to come to Arafat, stand there, and then proceed from it. This is the meaning of His statement, "Then depart from where the people depart" [Baqarah 2:199].
كانت قريش ومن دان دينها يقفون بالمزدلفة، وكانوا يسمون الحمس، وكان سائر العرب يقفون بعرفات، فلما جاء الإسلام أمر الله نبيه ﷺ أن يأتي بعرفات، ثم يقف بها، ثم يفيض منها، فذلك قوله تعالى: {ثم أفيضوا من حيث أفاض الناس}
Bukhari narrated it in tafsir (4520) and Muslim in Hajj (1219), both from the hadith of Muhammad bin Khazim Abu Muawiya, who said, "Hisham narrated to us, from his father, from Ayesha," and he mentioned it.His saying, "the Hums," refers to Quraysh and those whom Quraysh gave birth to. They were called Hums because they were strict (tahammasu) in their religion, meaning they were rigorous.