Musnad Ahmad 172:4

Yahya ibn Sa'id al-Umawi narrated to us, he said: Yahya ibn Sa'id narrated to us, from Sa'id ibn al-Musayyib, from Ma'mar al-'Adawi, he said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "No one hoards except a sinner." And Sa'id ibn al-Musayyib used to hoard oil.