It is narrated from al-Aswad and Abd al-Rahman bin Yazid that one of them accompanied Sayyiduna Umar (may Allah be pleased with him) and the other accompanied Abdullah (may Allah be pleased with him). Both mentioned that those two did not pray Maghrib until they halted at Muzdalifah; then they prayed Maghrib with one adhan and one iqamah, then they had their evening meal, then both prayed (Isha) with one adhan and one iqamah.
This chain is sahih (authentic).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1886