Sunan Abi Dawud 510
Narrated Abdullah ibn Umar:
The words of adhan were pronounced from the time of the Messenger of Allah (ﷺ) twice in pairs (i.e. four times) each, and the words of iqamah were pronounced once in pairs (twice each), except that the phrase "The time for prayer has come" would be pronounced twice. When we heard iqamah, we would perform ablution, and go out for prayer. Shu'bah said: I did not hear AbuJa'far narrating any other tradition except this one.
حَدَّثَنَا مُحَمَّدُ بْنُ بَشَّارٍ، حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، حَدَّثَنَا شُعْبَةُ، سَمِعْتُ أَبَا جَعْفَرٍ، يُحَدِّثُ عَنْ مُسْلِمٍ أَبِي الْمُثَنَّى، عَنِ ابْنِ عُمَرَ، قَالَ إِنَّمَا كَانَ الأَذَانُ عَلَى عَهْدِ رَسُولِ اللَّهِ صلى الله عليه وسلم مَرَّتَيْنِ مَرَّتَيْنِ وَالإِقَامَةُ مَرَّةً مَرَّةً غَيْرَ أَنَّهُ يَقُولُ قَدْ قَامَتِ الصَّلاَةُ قَدْ قَامَتِ الصَّلاَةُ فَإِذَا سَمِعْنَا الإِقَامَةَ تَوَضَّأْنَا ثُمَّ خَرَجْنَا إِلَى الصَّلاَةِ ‏.‏ قَالَ شُعْبَةُ وَلَمْ أَسْمَعْ مِنْ أَبِي جَعْفَرٍ غَيْرَ هَذَا الْحَدِيثِ ‏.‏