Sunan ad-Darimi 1229
Sahl b. Ḥammād > Shuʿbah > Abū Jaʿfar > Muslim Abū al-Muthanná > Ibn ʿUmar
"I asked Ibn 'Umar about the Adhan and he said: 'At the time of the Messenger of Allah ﷺ, the phrases of the Adhan were recited twice and the phrases of Iqamah once, except that you should say (the phrase) Qad qamat is-salah (prayer is about to begin)twice. When we heard 'prayer is about to begin' we would perform Wudu' and go out to pray.'" – Fair Chain
أَخْبَرَنَا سَهْلُ بْنُ حَمَّادٍ حَدَّثَنَا شُعْبَةُ حَدَّثَنَا أَبُو جَعْفَرٍ عَنْ مُسْلِمٍ أَبِي الْمُثَنَّى عَنِ ابْنِ عُمَرَ
أَنَّهُ قَالَ كَانَ الْأَذَانُ عَلَى عَهْدِ رَسُولِ اللَّهِ ﷺ مَثْنَى مَثْنَى وَالْإِقَامَةُ مَرَّةً غَيْرَ أَنَّهُ كَانَ إِذَا قَالَ قَدْ قَامَتِ الصَّلَاةُ قَالَهَا مَرَّتَيْنِ فَإِذَا سَمِعْنَا الْإِقَامَةَ تَوَضَّأَ أَحَدُنَا وَخَرَجَ – إسناده جيد