بُلُوغُ الْمَرَامِ
Bulugh al-Maram 187
The Book of Prayer
وَلَهُ عَنْ جَابِرٍ; { أَنَّ اَلنَّبِيَّ - صلى الله عليه وسلم -أَتَى اَلْمُزْدَلِفَةَ فَصَلَّى بِهَا اَلْمَغْرِبَ وَالْعِشَاءَ, بِأَذَانٍ وَاحِدٍ وَإِقَامَتَيْنِ } [1] .
Muslim also reported from Jabir (RA): The Prophet (ﷺ) came to al-Muzdalifah and offered at it both the Maghrib and 'Isha prayers with one Adhan and two Iqamah.
Sunnah.com reference: Book 2, Hadith 47