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:

Wesley's Notes

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

Jamieson-Fausset-Brown Bible Commentary

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.

Matthew Henry's Concise Commentary

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.