Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) said that the Messenger of Allah (peace and blessings be upon him) combined Maghrib and Isha at Muzdalifah; he did not have the adhan given between them, only the iqamah, and he did not offer any voluntary prayer between them, nor afterwards.
Imam al-Bukhari (may Allah have mercy on him) has recorded in his Sahih a narration from Ibn Abi Dhi'b that he (peace and blessings be upon him) combined Maghrib and Isha, with a separate iqamah for each.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9493
Ibn Umar (may Allah be pleased with them both) said that the Prophet (peace and blessings be upon him) prayed these two prayers combined at Muzdalifah, each with a separate iqamah, and he did not offer any voluntary prayer before or after either of them.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9494
Ibn Umar (may Allah be pleased with them both) said that the Prophet (peace and blessings be upon him) combined Maghrib and Isha and had the iqamah called for each one.
The difference among the narrators in this hadith has already passed in the Book of Prayer.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9495
Sayyiduna Ibn Umar (may Allah be pleased with them both) combined Maghrib and Isha at Muzdalifah, and it was said to him: O Abu Abd al-Rahman! What kind of prayer is this? He said: "I combined these two prayers, three rak'ahs of Maghrib and two rak'ahs of Isha, with the Prophet (peace and blessings be upon him) at this place with a single iqamah."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9496