Abu Ishaq reported,
I heard Abdulrahman bin Yazid say, "Abdullah 
performed the Hajj, and we arrived at Muzdalifa around the time of the Isha call to prayer, or close to it. He ordered a man to call the adhan and the iqama, then he prayed Maghrib and prayed two rak'ahs after it. Then he called for his dinner and ate. After that he ordered, I believe, the adhan and the iqama to be called."Amr said, "I only know the doubt to be from Zuhayr.""Then he prayed Isha as two rak'ahs. When dawn broke, he said, 'The Prophet ﷺ would not pray at this hour except for this prayer in this place on this day.'"Abdullah said, "There are two prayers that are shifted from their usual times, the Maghrib prayer, which is delayed until people arrive at Muzdalifa, and the Fajr prayer, which is performed as soon as dawn appears." He said, "I saw the Prophet ﷺ do this."
Azami 5141
Sahihعن أبي إسحاق: قال
سمعت عبد الرحمن بن يزيد يقول: حج عبد الله رضي الله عنه، فأتينا المزدلفة حين الأذان بالعتمة أو قريبا من ذلك فأمر رجلا فأذن وأقام، ثم صلى المغرب وصلى بعدها ركعتين، ثم دعا بعشائه فتعشى ثم أمر- أرى- فأذن وأقام. قال عمرو: لا أعلم الشك إلا من زهير- ثم صلى العشاء ركعتين فلما طلع الفجر قال: إن النبي ﷺ كان لا يصلي هذه الساعة إلا هذه الصلاة في هذا المكان من هذا اليوم. قال عبد الله: هما صلاتان تحولان عن وقتها صلاة المغرب بعد ما يأتي الناس المزدلفة، والفجر حين يبزغ الفجر. قال: رأيت النبي ﷺ يفعله.
Bukhari related it in the Hajj chapter (1675) from Amr bin Khalid, who said, Zuhayr narrated to us, who said, Abu Ishaq narrated to us, who said (then he mentioned it). This is also how Bukhari titled the chapter, as if he held the view that every prayer should have its own adhan and iqama.Perhaps the reason for this is that Ibn Masud created a separation between the two prayers, for he prayed Maghrib, then called for his dinner and ate it. This means that his companions dispersed for dinner and to attend to other needs, so in this situation a new adhan became necessary in order to gather the people together, after which he would give the iqama and pray. In this scenario, performing the two prayers with two calls to prayer and two calls to start is preferable to performing them with a single call to prayer and two calls to start.Something similar has been reported as the practice of Umar bin Khattab, as Tahawi recorded with a sahih chain of transmission, and this is the view held by Malik, may Allah have mercy on him.Hafiz bin Abdul-Barr reported from Ahmad bin Khalid that he used to marvel at Malik for adopting the hadith of Ibn Masud, which comes through the transmission of the people of Kufa despite being a mawquf report, while setting aside what was reported from the people of Madinah, which is a marfu report.Ibn Abdul-Barr said, "And I marvel at the people of Kufa, for they adopted what the people of Madinah reported, namely that the two prayers should be combined with a single adhan and a single iqama, while abandoning what they themselves reported on this matter from Ibn Masud, even though they consider no one his equal." See Fath al-Bari (3/525).As for the voluntary prayer after Maghrib or after Isha, nothing marfu has been reported on this matter. Rather, it is established in the sahih hadith that he performed no prayer between the two, and what has been established on this point comes only from the practice of some of the companions.As for the Witr prayer, it has likewise not been reported from the Prophet ﷺ that he prayed Witr on that night, neither in the hadith of Jabir nor in the hadiths of others who described the Prophet's ﷺ Hajj. But if someone were to pray Witr on that night, based on the established principle from the Prophet ﷺ that he never used to abandon Witr whether traveling or at home, that would be permissible. This is the view held by His Eminence Shaykh bin Baz. See his Fatawa (17/282–283).