Sahih Muslim 1288 c
Shu'ba reported this hadith with the same chain of transmitters and said:
He (the Holy Prophet) observed the two prayers (together) with one iqama.
وَحَدَّثَنِيهِ زُهَيْرُ بْنُ حَرْبٍ، حَدَّثَنَا وَكِيعٌ، حَدَّثَنَا شُعْبَةُ، بِهَذَا الإِسْنَادِ وَقَالَ صَلاَّهُمَا بِإِقَامَةٍ وَاحِدَةٍ ‏.‏