It is narrated from Sayyiduna Jarir (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said, concerning the saying of Allah Almighty: "And glorify with the praise of your Lord before the rising of the sun and before its setting" [Surah Ta Ha: 130]: "(The prayer) before the rising of the sun is the Fajr prayer, and (the prayer) before its setting is the Asr prayer."
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 2270