أَخْبَرَنَا سُوَيْدٌ، قَالَ حَدَّثَنَا عَبْدُ اللَّهِ، عَنْ يُونُسَ بْنِ أَبِي إِسْحَاقَ، عَنْ مُحَارِبِ بْنِ دِثَارٍ، قَالَ حَدَّثَنِي الأَسْوَدُ بْنُ يَزِيدَ، عَنْ أَبِي مَحْذُورَةَ، أَنَّ آخِرَ الأَذَانِ، لاَ إِلَهَ إِلاَّ اللَّهُ ‏.‏

It was narrated that Muharib bin Dithar said: "Al-Aswad bin Yazid narrated to me from Abu Mahdhurah that the final words of the Adhan are: 'La ilaha illahha (there is none worthy of worship except Allah).'" Translation Not Available

Book Ref: Sunan An Nisai Book 7 Hadith 659
Web Ref:  Sunan An Nisai Vol 1 Book 7 Hadith 653