This prayer is taken from Sayyidi Habib Umar bin Hafiz’s collection of prayers using Allah’s beautiful names in which he calls upon Allah by His beautiful names and then asks Him to bestow prayers upon His Beloved by those names. Finally, he asks Allah for a portion of those attributes which belong to Allah and which He has bestowed upon His Messenger ﷺ.
اللَّهُمَّ يا اللهُ يا غَفَّارُ صَلِّ على عَبْدِكَ و حَبِيبِكَ سَيِّدِنا مُحَمَّدٍ النَّبِيِّ مِفْتَاحِ بابِ مَغْفِرَتِكَ و على آلِهِ و صَحْبِهِ و سَلِّمْ تَسْلِيماً و اغْفِرْلِي بِهِ ما تَقَدَّمَ مِنْ ذَنْبِي و ما تَأَخَّرَ غُفْراناً
Allāhumma yā Allāhu yā Ghaffār ṣalli ‘alā ‘abdika wa ḥabībika sayyidinā Muḥammad an-nabī miftāḥi bābi maghfiratik wa ‘alā ālihi wa ṣaḥbihi wa sallim tasliman w’aghfirlī bihi mā taqaddama min dhanbī wa mā ta’akhkhara ghufrānā
O Allah, O Ever-Forgiving, bestow abundant prayers and peace upon Your slave and beloved, our Master Muhammad, the Prophet, the key to the door of Your forgiveness and upon his Family and Companions, and by him completely forgive me my past and future sins.