Musnad Abu Ya'la al-Mawsili 6:42

Zuhayr narrated to us, Waki' narrated to us, Sufyan narrated to us, from Sa'd ibn Ibrahim, from 'Amir, from his father, that the Prophet (peace and blessings of Allah be upon him) said: "Indeed, whatever expenditure you spend upon your family, you will be rewarded for it, even the morsel that you lift to the mouth of your wife."