The Command to say the phrases of the Adhan twice and the phrases of the iqamah once, except the phrase, "Prayer is about to begin," which is to be said twice
وَحَدَّثَنِي مُحَمَّدُ بْنُ حَاتِمٍ، حَدَّثَنَا بَهْزٌ، حَدَّثَنَا وُهَيْبٌ، حَدَّثَنَا خَالِدٌ الْحَذَّاءُ، بِهَذَا الإِسْنَادِ لَمَّا كَثُرَ النَّاسُ ذَكَرُوا أَنْ يُعْلِمُوا . بِمِثْلِ حَدِيثِ الثَّقَفِيِّ غَيْرَ أَنَّهُ قَالَ أَنْ يُورُوا نَارًا .
This hadith is transmitted by Khalid Hadhdha with the same chain of transmitters (and the words are): When the majority of the people discussed they should know, like the hadith narrated by al-Thaqafi (mentioned above) except for the words:" They (the people) should kindle fire."