Musnad Ahmad 26:336

'Abd al-Razzaq narrated to us, Sufyan informed us, from Mansur, from Abu Wa'il, from Ibn Mas'ud, who said: A man said to the Prophet, peace and blessings of Allah be upon him: "Will one of us be held accountable for what he did during the Jahiliyyah (pre-Islamic period)?" He said: "Whoever does good in Islam will not be held accountable for what he did during the Jahiliyyah, and whoever does evil in Islam will be held accountable for the first and the last."