Thus, therefore, you also, if you have brought a word in praise of God, not new and fresh from the learning of the spirit, from the doctrine of God's grace, your mouth indeed offers "a sacrifice of praise," but your mind is accused on account of the sterility of yesterday's flesh. For the Lord did not delay and order the bread which he gave to the disciples to be reserved for the next day when he said to them, "Take and eat." Perhaps there is something of this mystery in the fact that "he commands them not to carry bread on the way," that you always bring fresh loaves of the word of God which you carry within you. For this reason, the Gibeonites are condemned, and they become "cutters of wood and carriers of water" because they had brought old bread to the Israelites whom the spiritual law ordered always to use fresh and new.
Source: HOMILIES ON LEVITICUS 5.8