Musannaf Ibn Abi Shayba 3:1072

'Isa ibn Yunus and Waki' narrated to us, from al-Awza'i, from Yahya ibn Abi Kathir, from Abu Qilabah, from Abu al-Muhajir, from Buraydah al-Aslami, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Whoever misses the 'Asr prayer, his deeds are rendered void."