4 Then you will know which way to go, since you have never been this way before. But keep a distance of about two thousand cubitsa between you and the ark; do not go near it.”

Read Joshua 3:4 Using Other Translations

Yet there shall be a space between you and it, about two thousand cubits by measure: come not near unto it, that ye may know the way by which ye must go: for ye have not passed this way heretofore.
Yet there shall be a distance between you and it, about 2,000 cubits in length. Do not come near it, in order that you may know the way you shall go, for you have not passed this way before."
Since you have never traveled this way before, they will guide you. Stay about half a mile behind them, keeping a clear distance between you and the Ark. Make sure you don’t come any closer.”