Tuesday of the second week after Epiphany: Ezekiel 13.
This is Ezekiel’s denunciation of false prophets in Israel. It includes these words:
10 “Because, indeed, because they have seduced My people, saying, ‘Peace!’ when there is no peace—and one builds a wall, and they plaster it with untempered mortar— 11 say to those who plaster it with untempered mortar, that it will fall. There will be flooding rain, and you, O great hailstones, shall fall; and a stormy wind shall tear it down. 12 Surely, when the wall has fallen, will it not be said to you, ‘Where is the mortar with which you plastered it?’”
13 Therefore thus says the Lord GOD: “I will cause a stormy wind to break forth in My fury; and there shall be a flooding rain in My anger, and great hailstones in fury to consume it. 14 So I will break down the wall you have plastered with untempered mortar, and bring it down to the ground, so that its foundation will be uncovered; it will fall, and you shall be consumed in the midst of it. Then you shall know that I am the LORD.
Now, the whole phrase “they plaster it with untempered mortar” in the LXX is a single word in Greek: αλειφουσιν (see here), which occurs only in Ezekiel 13.
It is a peculiar enough idea that I wonder if it might not also be behind Paul’s denunciation of the high priest in Acts 23:3. Granted, the Greek is different: Paul calls the high priest a τοίχος κεκονιαμενος (literally, “a wall sprinkled with dust”). This is usually taken quite simply as an accusations of duplicitous hypocrisy (see here for the usual interpretation). On this view, Paul’s metaphor is similar to Jesus’ epithet “whitewashed tombs”, with he applies to the Pharisees in Matthew 23:27. But in that case, the point is more about the inside vs. the outside, and it’s not clear to me that that is what Paul means about the high priest.
If Paul is referencing Ezekiel 13:10 (and remember, if there were other translations than the LXX, it is even possible that he is quoting them), then the meaning of the phrase is different: it would denounce the high priest as a false prophet who bids the people ignore the wrath to come.
(Sorry for the overly technical note. I’ve got plaster on the brain right now after refinishing the kitchen walls in our 104 year old home!)