Mishkat al-Masabih 4 Prayer كتاب الصلاة 451

وَعَن ابْنِ عُمَرَ أَنَّهُ قَالَ: إِنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَرَأَ عَامَ الْفَتْحِ سَجْدَةً فَسَجَدَ النَّاسُ كُلُّهُمْ مِنْهُمُ الرَّاكِبُ وَالسَّاجِدُ عَلَى الْأَرْضِ حَتَّى إِنَّ الرَّاكِبَ لَيَسْجُدُ عَلَى يَده. رَوَاهُ أَبُو دَاوُد

He said that in the year of the Conquest* God’s Messenger recited a verse at which a prostration should be made and all the people prostrated themselves. Some were mounted, some were prostrating themselves on the ground, and those who were mounted prostrated themselves on their hands. * i.e. the Conquest of Mecca in 8 A.H. Abu Dawud transmitted it.