Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) said: We were with the Messenger of Allah (peace and blessings be upon him) on the day of the Trench (Khandaq), and he (peace and blessings be upon him) said: "May Allah Almighty fill with fire the houses and the graves of (those polytheists) who did not let us offer the middle prayer until the sun set; it was the Asr prayer."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2160