Reference : Hisn al-Muslim 25
اللّهُـمَّ رَبَّ هَذِهِ الدّعْـوَةِ التّـامَّة
وَالصّلاةِ القَـائِمَة
آتِ محَـمَّداً الوَسيـلةَ وَالْفَضـيلَة
وَابْعَـثْه مَقـامـاً مَحـموداً الَّذي وَعَـدْتَه
[إِنَّـكَ لا تُـخْلِفُ الميـعاد]
Allāhumma rabba hādhihi 'd-da'wati 't-tāmmah
waṣ-ṣalāti 'l-qā'imah, 
'āti Muhammadani 'l-wasīlata walfaḍīlata,
wab 'ath-hu maqāma 'm-mahmūdani 'l-ladhī wa`adtahu, 
['innaka lā tukhliful-mī'ād]

O Allah , Lord of this perfect call 
and established prayer. 
Grant Muhammad the intercession and favor,
and raise him to the honored station You have promised him, 
[verily You do not neglect promises].

Reference:
Al-Bukhari 1/152, and the addition between brackets is from Al-Bayhaqi 
1/410 with a good (Hasan) chain of narration. See 'Abdul-Azlz bin Baz's 
Tuhfatul-'Akhyar, pg. 38.

Chapter: Concerning the athan (the call to prayer)