Narrated by:Ibn 'Umar that Hafsah told him
It was narrated from Ibn 'Umar that Hafsah told him:"When he was called to Subh prayer, the Messenger of Allah (ﷺ) would do two prostrations before Subh prayer."
أَخْبَرَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ عَبْدِ الْحَكَمِ، قَالَ أَنْبَأَنَا إِسْحَاقُ بْنُ الْفُرَاتِ، عَنْ يَحْيَى بْنِ أَيُّوبَ، قَالَ حَدَّثَنِي يَحْيَى بْنُ سَعِيدٍ، قَالَ أَنْبَأَنَا نَافِعٌ، عَنِ ابْنِ عُمَرَ، عَنْ حَفْصَةَ، أَنَّهَا أَخْبَرَتْهُ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ إِذَا نُودِيَ لِصَلاَةِ الصُّبْحِ سَجَدَ سَجْدَتَيْنِ قَبْلَ صَلاَةِ الصُّبْحِ .
Nesai
The Book of Qiyam Al-Lail (The Night Prayer) and Voluntary Prayers During the Day • Hadith 1771