14 Let us see, then, the answer made by the Truth: “My Father works hitherto, and I work.” Is it false, then, which the Scripture has said, that “God rested from all His works on the seventh day”? And does the Lord Jesus speak contrary to this Scripture ministered by Moses, while He Himself says to the Jews, “If you believed Moses, you would believe me; for He wrote of me”? See, then, whether Moses did not mean it to be significant of something that “God rested on the seventh day.”
For God had not become wearied in doing the work of His own creation, and needed rest as a man. How can He have been wearied, who made by a word? Yet is both that true, that “God rested from His works on the seventh day;” and this also is true that Jesus says, “My Father works hitherto.” But who can unfold it in words, man to men, weak to weak, unlearned to them that seek to learn; and if he chance to understand somewhat, unable to bring it forth and unfold it to men, who with difficulty, it may be, receive it, even if what is received can possibly be unfolded?
Who, I say, my brethren, can unfold in words how God both works while at rest, and rests while working? I pray you to put this matter off while you are advancing on the way; for this seeing requires the temple of God, requires the holy place. Bear your neighbor, and walk. You shall see Him in that place where you shall not require the words of men.
Source: Tractates on the Gospel of John (New Advent)