A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
jdg 18:1THE DANITES SEEK OUT AN INHERITANCE. (Jdg. 18:1-26)
In those days . . . the Danites sought them an inheritance to dwell in--The Danites had a territory assigned them as well as the other tribes. But either through indolence, or a lack of energy, they did not acquire the full possession of their allotment, but suffered a considerable portion of it to be wrested out of their hands by the encroachments of their powerful neighbors, the Philistines. In consequence, being straitened for room, a considerable number resolved on trying to effect a new and additional settlement in a remote part of the land. A small deputation, being despatched to reconnoitre the country, arrived on their progress northward at the residence of Micah. Recognizing his priest as one of their former acquaintances, or perhaps by his provincial dialect, they eagerly enlisted his services in ascertaining the result of their present expedition. His answer, though apparently promising, was delusive, and really as ambiguous as those of the heathen oracles. This application brings out still more clearly and fully than the schism of Micah the woeful degeneracy of the times. The Danites expressed no emotions either of surprise or of indignation at a Levite daring to assume the priestly functions, and at the existence of a rival establishment to that of Shiloh. They were ready to seek, through means of the teraphim, the information that could only be lawfully applied for through the high priest's Urim. Being thus equally erroneous in their views and habits as Micah, they show the low state of religion, and how much superstition prevailed in all parts of the land.
jdg 18:7the five men departed, and came to Laish--or, "Leshem" (Jos 19:47), supposed to have been peopled by a colony of Zidonians. The place was very secluded--the soil rich in the abundance and variety of its produce, and the inhabitants, following the peaceful pursuits of agriculture, lived in their fertile and sequestered valley, according to the Zidonian style of ease and security, happy among themselves, and maintaining little or no communication with the rest of the world. The discovery of this northern paradise seemed, to the delight of the Danite spies, an accomplishment of the priest's prediction. They hastened back to inform their brethren in the south both of the value of their prize, and how easily it could be made their prey.
jdg 18:11there went from thence of the family of the Danites . . . six hundred men--This was the collective number of the men who were equipped with arms to carry out this expeditionary enterprise, without including the families and furniture of the emigrants (Jdg 18:21). Their journey led them through the territory of Judah, and their first halting place was "behind," that is, on the west of Kirjath-jearim, on a spot called afterwards "the camp of Dan." Prosecuting the northern route, they skirted the base of the Ephraimite hills. On approaching the neighborhood of Micah's residence, the spies having given information that a private sanctuary was kept there, the priest of which had rendered them important service when on their exploring expedition, it was unanimously agreed that both he and the furniture of the establishment would be a valuable acquisition to their proposed settlement. A plan of spoliation was immediately formed. While the armed men stood sentinels at the gates, the five spies broke into the chapel, pillaged the images and vestments, and succeeded in bribing the priest also by a tempting offer to transfer his services to their new colony. Taking charge of the ephod, the teraphim, and the graven image, he "went in the midst of the people"--a central position assigned him in the march, perhaps for his personal security; but more probably in imitation of the place appointed for the priests and the ark, in the middle of the congregated tribes, on the marches through the wilderness. This theft presents a curious medley of low morality and strong religious feeling. The Danites exemplified a deep-seated principle of our nature--that men have religious affections, which must have an object on which these may be exercised, while they are often not very discriminating in the choice of the objects. In proportion to the slender influence religion wields over the heart, the greater is the importance attached to external rites; and in the exact observance of these, the conscience is fully satisfied, and seldom or never molested by reflections on the breach of minor morals.
jdg 18:22the men that were in the houses near to Micah's house were gathered together--The robbers of the chapel being soon detected, a hot pursuit was forthwith commenced by Micah, at the head of a considerable body of followers. The readiness with which they joined in the attempt to recover the stolen articles affords a presumption that the advantages of the chapel had been open to all in the neighborhood; and the importance which Micah, like Laban, attached to his teraphim, is seen by the urgency with which he pursued the thieves, and the risk of his life in attempting to procure their restoration. Finding his party, however, not a match for the Danites, he thought it prudent to desist, well knowing the rule which was then prevalent in the land, that
"They should take who had the power,
And they should keep who could."
jdg 18:27THEY WIN LAISH. (Jdg 18:27-29)
they . . . came unto Laish . . . smote them--the inhabitants.
and burnt the city--"We are revolted by this inroad and massacre of a quiet and secure people. Nevertheless, if the original grant of Canaan to the Israelites gave them the warrant of a divine commission and command for this enterprise, that sanctifies all and legalizes all" [CHALMERS]. This place seems to have been a dependency of Zidon, the distance of which, however, rendered it impossible to obtain aid thence in the sudden emergency.
jdg 18:28they built a city, and . . . call the name of that city Dan--It was in the northern extremity of the land, and hence the origin of the phrase, "from Dan to Beer-sheba."
jdg 18:30THEY SET UP IDOLATRY. (Jdg 18:30-31)
the children of Dan set up the graven image--Their distance secluded them from the rest of the Israelites, and doubtless this, which was their apology for not going to Shiloh, was the cause of perpetuating idolatry among them for many generations.