أَخْبَرَنَا الْعَبَّاسُ بْنُ عَبْدِ الْعَظِيمِ، قَالَ أَنْبَأَنَا عُمَرُ بْنُ يُونُسَ، قَالَ حَدَّثَنَا عِكْرِمَةُ بْنُ عَمَّارٍ، قَالَ حَدَّثَنِي يَحْيَى بْنُ أَبِي كَثِيرٍ، قَالَ حَدَّثَنِي أَبُو سَلَمَةَ بْنُ عَبْدِ الرَّحْمَنِ، قَالَ سَأَلْتُ عَائِشَةَ بِأَىِّ شَىْءٍ كَانَ النَّبِيُّ صلى الله عليه وسلم يَفْتَتِحُ صَلاَتَهُ قَالَتْ كَانَ إِذَا قَامَ مِنَ اللَّيْلِ افْتَتَحَ صَلاَتَهُ قَالَ ‏"‏ اللَّهُمَّ رَبَّ جِبْرِيلَ وَمِيكَائِيلَ وَإِسْرَافِيلَ فَاطِرَ السَّمَوَاتِ وَالأَرْضِ عَالِمَ الْغَيْبِ وَالشَّهَادَةِ أَنْتَ تَحْكُمُ بَيْنَ عِبَادِكَ فِيمَا كَانُوا فِيهِ يَخْتَلِفُونَ اللَّهُمَّ اهْدِنِي لِمَا اخْتُلِفَ فِيهِ مِنَ الْحَقِّ إِنَّكَ تَهْدِي مَنْ تَشَاءُ إِلَى صِرَاطٍ مُسْتَقِيمٍ ‏"‏ ‏.‏

Abu Salamah bin 'Abdur-Rahman said: "I asked 'Aishah: 'With what did the Prophet (PBUH) start his prayer?' She said: 'When he got up to pray at night he would start his prayer with the words: Allahumma Rabba Jibril wa Maika'il wa Israfil; Fatirus-samawati wal-ard, 'alim al-ghaybi wash-shahadah, anta tahkumu bayna 'ibadika fima kanu fihi yakhtalifun, Allahumma ihdini limakktulifa fihi min al-haqq innaka tahdi man tasha'ila siratin mustaqim (O Allah, Lord of Jibril, Mika'il and Israfil, Creator of the heavens and the earth, Knower of the unseen and the seen, You judge between Your slaves concerning wherein they differ. O Allah, guide me to the disputed matters of truth for You are the One Who guides to the Straight Path)." Translation Not Available

Book Ref: Sunan An Nisai Book 20 Hadith 1625
Web Ref:  Sunan An Nisai Vol 2 Book 20 Hadith 1626