Purify yourselves translates the reflexive form of the Hebrew verb “be holy”; so “make yourselves holy”—that is, ritually pure, by undergoing some sort of ceremony which would effect the forgiveness of sins and remove all ritual impurity. This was a preparation for a cultic procession or a holy war (see similar instruction in Exo 19.10, 14-15). The concept of ritual or cultic purity is well-known in many cultures but unknown in many others. And even in cultures where this belief is found, the presuppositions may be quite different from those of the ancient Israelites. Therefore a footnote may be necessary. The translation may be handled quite well by going from general to specific, and then by following this with an explanation of the specific command: “Get yourselves ready! Be sure that you are pure, as the LORD demands of his people.”
Tomorrow appears strange in the context, since the narrative itself makes no mention of a day’s interval between the order for the people to purify themselves and the actual crossing. However, it is an evident part of the text and must be retained in translation. It was at the crossing that the Lord performed a miracle, namely, stopping the flow of the river.
Miracles translates a word meaning “wonderful things, extraordinary deeds.” Although the Hebrew does use the plural form “miracles,” this is probably done solely for the sake of intensifying the miraculous aspect of what the Lord was going to do. Since only one miracle is involved, it may be better to render “Tomorrow the LORD will work a miracle for you.” Or, if it is felt that the impact of the Hebrew plural form is not adequately conveyed by “a miracle,” one may render “a great miracle.”
Among you, which represents the form of the Hebrew, may be more effectively rendered “for you,” or better “for us,” to include Joshua. The phrase will perform miracles among you could convey the incorrect picture of the Lord as a miracle worker among the people of Israel, and that on the next day he would perform miracles among them in a number of different places.
Quoted with permission from Bratcher, Robert G. and Newman, Barclay M. A Handbook on Joshua. (UBS Helps for Translators). New York: UBS, 1983. For this and other handbooks for translators see here .