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.

Wesley's Notes

3:4 Two thousand cubits - A thousand yards, at which distance from it the Israelites seem to have been encamped in the wilderness. And because they generally went from their tents to the ark to worship God, especially on the sabbath - days; hence it hath been conceived, that a sabbath - day's journey reached only to two thousand cubits. But that may be doubted; for those who encamped nearest the ark, were at that distance from it, and came so far; but the rest were farther from it, and their sabbath - day's journey was considerably longer. Near unto it - Partly from the respect they should bear to the ark; but chiefly, that the ark marching so far before you into the river, and standing still there 'till you pass over, may give you the greater assurance of your safe passage. Ye have not passed this way heretofore - While we are here, we must expect unusual events, to pathways that we have not passed before: and much more when we go hence, when we pass thro' the valley of the shadow of death. But if we have the assurance of God's presence, what have we to fear?

King James Translators' Notes

heretofore: Heb. since yesterday, and the third day

Matthew Henry's Concise Commentary

3:1-6 The Israelites came to Jordan in faith, having been told that they should pass it. In the way of duty, let us proceed as far as we can, and depend on the Lord. Joshua led them. Particular notice is taken of his early rising, as afterwards upon other occasions, which shows how little he sought his own ease. Those who would bring great things to pass, must rise early. Love not sleep, lest thou come to poverty. All in public stations should always attend to the duty of their place. The people were to follow the ark. Thus must we walk after the rule of the word, and the direction of the Spirit, in everything; so shall peace be upon us as upon the Israel of God; but we must follow our ministers only as they follow Christ. All their way through the wilderness was an untrodden path, but most so this through Jordan. While we are here, we must expect and prepare to pass ways that we have not passed before; but in the path of duty we may proceed with boldness and cheerfulness. Whether we are called to suffer poverty, pain, labour, persecution, reproach, or death, we are following the Author and Finisher of our faith; nor can we set our feet in any dangerous or difficult spot, through our whole journey, but faith will there see the prints of the Redeemer's feet, who trod that very path to glory above, and bids us follow him, that where he is, we may be also. They were to sanctify themselves. Would we experience the effects of God's love and power, we must put away sin, and be careful not to grieve the Holy Spirit of God.