Musnad Ahmad 30:3044

Waki’ narrated to us, Sufyan narrated to us, from Muzahim ibn Zafar, from Mujahid, from Abu Hurairah, who said: The Prophet, peace and blessings of Allah be upon him, said: "A dinar you spent in the way of Allah, and a dinar you spent to free a slave, and a dinar you gave as charity, and a dinar you spent on your family; the best of them is the dinar you spent on your family."