"When the "Surat-An-Nasr", 'When comes the Help of Allah and the conquest,' had been revealed to the Prophet ﷺ he did not offer any prayer except that he said therein, "Subhanka Rabbana wa bihamdika; Allahumma ighfirli (I testify the Uniqueness of our Lord, and all the praises are for Him: O Allah, forgive me!")  

مَا صَلَّى النَّبِيُّ ﷺ صَلاَةً بَعْدَ أَنْ نَزَلَتْ عَلَيْهِ {إِذَا جَاءَ نَصْرُ اللَّهِ وَالْفَتْحُ} إِلاَّ يَقُولُ فِيهَا سُبْحَانَكَ رَبَّنَا وَبِحَمْدِكَ اللَّهُمَّ اغْفِرْ لِي  

[Machine] When the victory of Allah and the conquest come (i.e., when the help of Allah and the conquest of Makkah occurred), the Prophet ﷺ used to frequently say: "Subhanaka Allahumma wa bihamdika Allahumma, ighfir li innaka antat-Tawwab (Glory be to You, O Allah, and all praise is due to You, O Allah, forgive me for You are the Most Forgiving.)"  

لَمَّا نَزَلَتْ إِذَا جَاءَ نَصْرُ اللهِ وَالْفَتْحُ كَانَ النَّبِيُّ ﷺ يُكْثِرُ أَنْ يَقُولَ سُبْحَانَكَ اللهُمَّ وَبِحَمْدِكَ اللهُمَّ اغْفِرْ لِي إِنَّكَ أَنْتَ التَّوَّابُ  

Never did I, see the Messenger of Allah ﷺ after the revelation (of these verses):" When Allah's help and victory came." observin- his prayer without making (this supplication) or he said in it (supplication): Hallowed be Thee, my Lord, and with Thy praise, O Allah, forgive me. (Using translation from Muslim 484c)  

مَا رَأَيْتُ النَّبِيَّ ﷺ مُنْذُ نَزَلَ عَلَيْهِ إِذَا جَاءَ نَصْرُ اللهِ وَالْفَتْحُ يُصَلِّي صَلَاةً إِلَّا دَعَا وَقَالَ سُبْحَانَكَ رَبِّي وَبِحَمْدِكَ اللهُمَّ اغْفِرْ لِي  

[Machine] "When the victory of Allah and the conquest came, I never saw the Messenger of Allah ﷺ praying any prayer except that he would say: 'Subhanak Allahumma wa bihamdika, Allahumma ighfirli.'"  

لَمَّا أُنْزِلَتْ إِذَا جَاءَ نَصْرُ اللهِ وَالْفَتْحُ إِلَى آخِرِهَا مَا رَأَيْتُ رَسُولَ اللهِ ﷺ صَلَّى صَلَاةً إِلَّا قَالَ سُبْحَانَكَ رَبَّنَا وَبِحَمْدِكَ اللهُمَّ اغْفِرْ لِي  

[Machine] "When the verse 'When the victory of Allah has come and the conquest' until the end of it was revealed, I did not see the Messenger of Allah ﷺ perform any prayer without saying, 'Subhanaka Allahumma wa bihamdika Allahumma ighfirli' meaning 'Glory be to You, O Allah, and all praise is due to You, O Allah, forgive me.'"  

لَمَّا نَزَلَتْ {إِذَا جَاءَ نَصْرُ اللَّهِ وَالْفَتْحُ} إِلَى آخِرِهَا مَا رَأَيْتُ رَسُولَ اللَّهِ ﷺ صَلَّى صَلَاةً إِلَّا قَالَ «سُبْحَانَكَ اللَّهُمَّ وَبِحَمْدِكَ اللَّهُمَّ اغْفِرْ لِي»  

"كَانَ رَسُولُ اللهِ ﷺ يُكْثِرُ أَنْ يَقُولَ فِي ركُوعِهِ وَسُجُودِهِ: سُبْحَانَكَ اللَّهُمَّ رَبَّنَا وَبِحَمْدِكَ، اللَّهُمَّ اغْفِر لِي - يَتَأَوَّلُ القُرْآنَ- يَعْنِي {إِذَا جَاءَ نَصْرُ اللَّهِ وَالْفَتْحُ} ".