(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." (JA)
Reference (JA): Sunan an-Nasa'i 1771 (JA)
In-book reference (JA): Book 20, Hadith 174 (JA)
English translation (JA): Vol. 2, Book 20, Hadith 1772 (JA)