Du'a when beginning Tawaf

اللَّهُمَّ إِيمَانًا بِكَ، وَتَصْدِيقًا بِكِتَابِكَ، وَسُنَّةِ نَبِيِّكَ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ

Allahumma imanan bika, wa tasdiqan bikitabika, wa sunnati nabiyyika sallal-lahu 'alayhi wa sallam

O Allah, out of faith in You, conviction in Your Book, and the Sunnah of Your Prophet, peace be upon him.

Adapted from al-Sunan al-Kubrā of al-Bayhaqī (5/79), which reads "اللَّهُمَّ إِيمَانًا بِكَ وَتَصْدِيقًا بِكِتَابِكَ وَوَفَاءً بِعَهْدِكَ وَاتِّبَاعًا لِسُنَّةِ نَبِيِّكَ مُحَمَّدٍ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ" (O Allah, out of faith in You, belief in Your Book, fulfilment of Your covenant and following the Sunnah of Your Prophet Muhammad, peace be upon him). This version omits "fulfilment of Your covenant" and shortens the last phrase.