Adam Clarke on Exodus 15:17

Thou shalt bring them in - By thy strength and mercy alone shall they get the promised inheritance.

And plant them - Give them a fixed habitation in Canaan, after their unsettled wandering life in the wilderness.

In the mountain - Meaning Canaan, which was a very mountainous country, Deu 11:11; or probably Mount Zion, on which the temple was built. Where the pure worship of God was established, there the people might expect both rest and safety. Wherever the purity of religion is established and preserved, and the high and the low endeavor to regulate their lives according to its precepts, the government of that country is likely to be permanent.