Musnad Ahmad 1017:110

'Abd al-Razzaq narrated to us, Ma'mar narrated to us, from Yahya ibn Abi Kathir, from Abu Qilabah, from Abu al-Malih ibn Usamah, from Buraydah, that the Prophet, peace and blessings of Allah be upon him, said: "Whoever leaves the 'Asr prayer intentionally, Allah will nullify his deeds."