The Prophet (sallallaahu `alayhi wasallam) offered the Maghrib and ‘Isha’ prayers together at Jam’ (i.e. Al-Muzdalifa) with a separate Iqama for each of them and did not offer any optional prayer in between them or after each of them.
Volume 2, Book 26, Number 734:
Narrated Abu Aiyub Al-Ansari (radiallaahu `anhu):
Allah’s Apostle (sallallaahu `alayhi wasallam) offered the Maghrib and ‘Isha’ prayers together at Al-Muzdalifa.
Volume 2, Book 26, Number 735:
Narrated ‘Abdur-Rahman bin Yazid:
‘Abdullah (radiallaahu `anhu) performed the Hajj and we reached Al-Muzdalifa at or about the time of the ‘Isha’ prayer. He ordered a man to pronounce the Adhan and Iqama and then he offered the Maghrib prayer and offered two Rakat after it. Then he asked for his supper and took it, and then, I think, he ordered a man to pronounce the Adhan and Iqama (for the ‘isha’ prayer). (‘Amr, a sub-narrator said: The intervening statement ‘I think’, was said by the sub-narrator Zuhair) (i.e. not by ‘Abdu-Rahman). Then ‘Abdullah (radiallaahu `anhu) offered two Rakat of ‘Isha’ prayer. When the day dawned, ‘Abdullah (radiallaahu `anhu) said, “The Prophet (sallallaahu `alayhi wasallam) never offered any prayer at this hour except this prayer at this time and at this place and on this day.” ‘Abdullah (radiallaahu `anhu) added, “These two prayers are shifted from their actual times — the Maghrib prayer (is offered) when the people reached Al-Muzdalifa and the Fajr (morning) prayer at the early dawn.” ‘Abdullah (radiallaahu `anhu) added, “I saw the Prophet (sallallaahu `alayhi wasallam) doing that.”
When the sun sets, the pilgrim should go to Muzdalifah. When he reaches there, he should pray Maghrib and ‘Isha’ with one adhaan and two iqaamahs. If he fears that he will not reach Muzdalifah before midnight, he should pray on the way, because it is not permissible to delay ‘Isha’ prayer until after midnight.
He should stay overnight in Muzdalifah, then when dawn comes he should pray Fajr early, with the adhaan and iqaamah, and then head for al-Mash’ar al-Haraam (which is the site of the mosque in Muzdalifah) and proclaim the oneness and greatness of Allaah (by saying Laa ilaaha ill-Allaah and Allaahu akbar), and making du’aa’ as he likes, until it has become very light (i.e., when the light of day appears before the sun has actually risen). If it is not easy for him to go to al-Mash’ar al-Haraam, he should make du’aa’ where he is, because the Prophet (peace and blessings of Allaah be upon him) stood there and all of Muzdalifah is the place of standing. When he is reciting dhikr and making du’aa’ he should face the qiblah and raise his hands.
Taken from: http://ilookilisten.wordpress.com/2013/03/19/hajj-muzdalifah-ahadith-1433-1435/