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