Tirmidhi 168

Agreed upon (by Bukhari and Muslim). Bukhari narrated it in the Book of Prayer Times, Chapter on the Time of Asr, hadith no. 547, from the hadith of Awf Arabi, and Muslim narrated it in the Book of Mosques, Chapter on the Recommendation of Praying Fajr Early at the Beginning of Its Time... etc., hadith no. 647, from the hadith of Yasar.There are also narrations on this subject from Ayesha [Ibn Majah, hadith no. 702], Abdullah bin Masud [Ibn Majah, hadith no. 703], and Anas [Abdul-Razzaq 1/563, hadith no. 2138, and Ibn Abu Shayba 2/280].