Deuteronomy 27:2

2. The day when ye shall pass over Jordan Day is used here, as elsewhere, to denote the time when. After you have passed over Jordan, thou shalt set thee up great stones, etc. Some have inferred that the law was first engraved upon the stones and then the stones covered with some kind of cement.

Plaster them The Hebrew word which our version renders plaster is so seldom met with that its meaning is not plain. In a dry climate, with little or no frost, the cement will remain intact for a long time. That on the so-called Pools of Solomon, which bear marks of great age, is in admirable preservation, as though only a few years old.