It is narrated from Hazrat Samurah (may Allah be pleased with him) that once someone asked the Prophet (peace and blessings be upon him), "What is meant by 'Salat al-Wusta'?" The Prophet (peace and blessings be upon him) replied, "The Asr prayer."
Hadith Referenceمسند احمد / أول مسند البصريين / 20082
Hadith Gradingحکم دارالسلام:صحيح لغيره، وهذا إسناد ضعيف، ولم يصرح الحسن بسماعه من سمرة