Narrated by:Al-Aswad that Bilal said
It was narrated from Al-Aswad that Bilal said:"The final words of the Adhan are: 'Allahu Akbar, Allahu Akbar; La ilaha illallah (Allah is the Greatest, Allah is the Greatest, there is none worthy of worship except Allah.)'"
أَخْبَرَنَا مُحَمَّدُ بْنُ مَعْدَانَ بْنِ عِيسَى، قَالَ حَدَّثَنَا الْحَسَنُ بْنُ أَعْيَنَ، قَالَ حَدَّثَنَا زُهَيْرٌ، قَالَ حَدَّثَنَا الأَعْمَشُ، عَنْ إِبْرَاهِيمَ، عَنِ الأَسْوَدِ، عَنْ بِلاَلٍ، قَالَ آخِرُ الأَذَانِ اللَّهُ أَكْبَرُ اللَّهُ أَكْبَرُ لاَ إِلَهَ إِلاَّ اللَّهُ .
Nesai
The Book of the Adhan (The Call to Prayer) • Hadith 649