Fiqh-us-Sunnah Volume 5, Hajj and ‘Umrah, Fiqh 5.101.

One may stop anywhere in Muzdalifah, except the valley called Muhassir (between Muzdalifah and Mina). Jubair bin Mot’im reported that the Prophet (peace be upon him) said: “The entire area of Muzdalifah is a place to stay, but avoid the valley called Muhassir.” This is reported by Ahmad with a sound chain of authorities. Spending the time at Muzdalifah at a place called Quzah, (The Quraish used to stop there in the pre-Islamic period instead of staying at Arafah) is, however, better.

In a hadith reported by Ali we read that when the Prophet (peace be upon him) arrived at Joma (a place in Muzdalifah), he stood there and said, “This is Quzah, the place to stop; and the entire Joma is a stopping place.” This is reported by Abu Daw’ud and Tirmizhi, who considers it a sound hadith.