It is narrated from Sayyiduna al-Bara' bin Azib (may Allah be pleased with him) that this verse was revealed: "Guard the prayers, especially the Asr prayer." For as long as Allah willed, we recited it in the time of the Messenger of Allah (peace and blessings be upon him). Then Allah abrogated it and revealed this: "Guard the prayers, especially the middle prayer." [Surah al-Baqarah: 238] A man asked al-Bara' bin Azib (may Allah be pleased with him): Is it the Asr prayer? He said: I have told you how it was revealed and how Allah abrogated it. And Allah knows best.
In Sahih Muslim this same report is transmitted from Fudayl, but in it the man said: Then it must be the Asr prayer. Al-Bara' bin Azib (may Allah be pleased with him) said: Did I not tell you how it was revealed and how Allah abrogated it?
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2158