Fortress of the Muslim (Hisn al-Muslim)
حصن المسلم
(9) Chapter: Upon completing the ablution
(9) الذكر بعد الفراغ من الوضوء
Hisn al-Muslim 13 
'Ash-hadu 'an lā 'ilāha 'illallāhu waḥdahu lā sharīka lahu wa 'ash-hadu 'anna Muḥammadan `abduhu wa Rasūluhu. I bear witness that none has the right to be worshipped but Allah alone, Who has no partner; and I bear witness that Muhammad is His slave and His Messenger. Reference: Muslim 1/209.
أَشْهَدُ أَنْ لا إِلَـهَ إِلاّ اللهُ وَحْدَهُ لا شَريـكَ لَـهُ وَأَشْهَدُأَنَّ مُحَمّـداً عَبْـدُهُ وَرَسـولُـه
Reference : Hisn al-Muslim 13