(60) باب وَقْتِ رَكْعَتَىِ الْفَجْرِ وَذِكْرِ الاِخْتِلاَفِ عَلَى نَافِعٍ
It was narrated that Ibn 'Abbas said:
"The Prophet (ﷺ) used to pray two rak'ahs of Fajr when he heard the Adhan and he made them brief." (ES)
Reference (ES): Sunan an-Nasa'i 1782 (ES)
In-book reference (ES): Book 20, Hadith 185 (ES)
English translation (ES): Vol. 2, Book 20, Hadith 1783 (ES)