(60) باب وَقْتِ رَكْعَتَىِ الْفَجْرِ وَذِكْرِ الاِخْتِلاَفِ عَلَى نَافِعٍ
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." (FR)
Reference (FR): Sunan an-Nasa'i 1771 (FR)
In-book reference (FR): Book 20, Hadith 174 (FR)
English translation (FR): Vol. 2, Book 20, Hadith 1772 (FR)