The stones here named are not those of which the altar Deuteronomy 27:5 was to be built, but are to serve as a separate monument witnessing to the fact that the people took possession of the land by virtue of the Law inscribed on them and with an acknowledgment of its obligations.

Thou shalt set thee up great stones - How many is not specified, possibly twelve, and possibly only a sufficient number to make a surface large enough to write the blessings and the curses on.

Plaster them with plaster - Perhaps the original ושדת אתם בשיד vesadta otham bassid should be translated, Thou shalt cement them with cement, because this was intended to be a durable monument. In similar cases it was customary to set up a single stone, or a heap, rudely put together, where no cement or mortar appears to have been used; and because this was common, it was necessary to give particular directions when the usual method was not to be followed. Some suppose that the writing was to be in relievo, and that the spaces between the letters were filled up by the mortar or cement. This is quite a possible case, as the Eastern inscriptions are frequently done in this way. There is now before me a large slab of basaltes, two feet long by sixteen inches wide, on which there is an inscription in Persian, Arabic, and Tamul; in the two former the letters are all raised, the surface of the stone being dug out, but the Tamul is indented. A kind of reddish paint had been smeared over the letters to make them more apparent. Two Arabic marbles in the University of Oxford have the inscriptions in relievo, like those on the slab of basalt in my possession. In the opinion of some even this case may cast light upon the subject in question

And it shall be, on the day when you shall pass over Jordan,.... Not the precise day exactly, but about that time, a little after they passed that river, as soon as they conveniently could; for it was not till after Ai was destroyed that the following order was put in execution; indeed as soon as they passed over Jordan, they were ordered to take twelve stones, and did; but then they were set up in a different place, and for a different purpose; see Joshua 4:3,

unto the land which the Lord thy God giveth thee, that thou shalt set thee up great stones; not in Jordan, as Jarchi, but on Mount Ebal, Deuteronomy 27:4; nor had the stones set up in Jordan any such inscription as what is here ordered to be set on these:

and plaster them with plaster: that so words might be written upon them, and be more conspicuous, and more easily read.

And it shall be on the day when ye shall pass over Jordan unto the land which the LORD thy God giveth thee, that thou shalt set thee up great stones, and plaster them with plaster:

27:2 On that day - About that time, for it was not done 'till some days after their passing over.

2. it shall be on the day when ye shall pass over Jordan-"Day" is often put for "time"; and it was not till some days after the passage that the following instructions were acted upon.

thou shalt set thee up great stones, and plaister them with plaister-These stones were to be taken in their natural state, unhewn, and unpolished-the occasion on which they were used not admitting of long or elaborate preparation; and they were to be daubed over with paint or whitewash, to render them more conspicuous. Stones and even rocks are seen in Egypt and the peninsula of Sinai, containing inscriptions made three thousand years ago, in paint or plaister. By some similar method those stones may have been inscribed, and it is most probable that Moses learned the art from the Egyptians.

27:1-10 As soon as they were come into Canaan, they must set up a monument, on which they must write the words of this law. They must set up an altar. The word and prayer must go together. Though they might not, of their own heads, set up any altar besides that at the tabernacle; yet, by the appointment of God, they might, upon special occasion. This altar must be made of unhewn stones, such as they found upon the field. Christ, our Altar, is a stone cut out of the mountain without hands, refused by the builders, as having no form or comeliness, but accepted of God the Father, and made the Head of the corner. In the Old Testament the words of the law are written, with the curse annexed; which would overcome us with horror, if we had not, in the New Testament, an altar erected close by, which gives consolation. Blessed be God, the printed copies of the Scriptures among us, do away the necessity of such methods as were presented to Israel. The end of the gospel ministry is, and the end of preachers ought to be, to make the word of God as plain as possible. Yet, unless the Spirit of God prosper such labours with Divine power, we shall not, even by these means, be made wise unto salvation: for this blessing we should therefore daily and earnestly pray.