28 Regarding the Sabbath and circumcision, and the distinction in foods, in which you say the teaching of Moses differs from what Christians are taught by Christ, we have already shown that, as the apostle says, "all those things were our examples." The difference is not in the doctrine, but in the time. There was a time when it was proper that these things should be figuratively predicted; and there is now a different time when it is proper that they should be openly declared and fully accomplished.
It is not surprising that the Jews, who understood the Sabbath in a carnal sense, should oppose Christ, who began to open up its spiritual meaning. Reply, if you can, to the apostle, who declares that the rest of the Sabbath was a shadow of something future. If the Jews opposed Christ because they did not understand what the true Sabbath is, there is no reason why you should oppose Him, or refuse to learn what true innocence is. For on that occasion when Jesus appears especially to set aside the Sabbath, when His disciples were hungry, and pulled the ears of grain through which they were passing, and ate them, Jesus, in replying to the Jews, declared His disciples to be innocent.
"If you knew," He said "what this means, I will have mercy, and not sacrifice, you would not have condemned the innocent." They should rather have pitied the wants of the disciples, for hunger forced them to do what they did. But pulling ears of grain, which is innocence in the teaching of Christ, is murder in the teaching of Manichæus. Or was it an act of charity in the apostles to pull the ears of grain, that they might in eating set free the members of God, as in your foolish notions?
Then it must be cruelty in you not to do the same. Faustus' reason for setting aside the Sabbath is because he knows that God's power is exercised without cessation, and without weariness. It is for those to say this, who believe that all times are the production of an eternal act of God's will. But you will find it difficult to reconcile this with your doctrine, that the rebellion of the race of darkness broke your god's rest, which was also disturbed by a sudden attack of the enemy; or perhaps God never had rest, as he foresaw this from eternity, and could not feel at ease in the prospect of so dire a conflict, with such loss and disaster to his members.
Source: Reply to Faustus the Manichaean (New Advent)