To eat of

partitive use).

See also: Eat

Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in classic literature ?
In this world, even as children, we must accustom ourselves to eat of everything, for we never know what life may hold in store for us!"
On one occasion when the disciples bring food to Jesus, he says dismissively, "I have food to eat of which you do not know." Perhaps he was recalling how the devil had come to him during a long fast and tempted him to turn stones into bread.