'Sand' in the Bible

Don't you fear me?' says Yahweh 'Won't you tremble at my presence, who have placed the sand for the bound of the sea, by a perpetual decree, that it can't pass it? and though its waves toss themselves, yet they can't prevail; though they roar, yet they can't pass over it.'

Their widows are increased to me above the sand of the seas; I have brought on them against the mother of the young men a destroyer at noonday: I have caused anguish and terrors to fall on her suddenly.

As the army of the sky can't be numbered, neither the sand of the sea measured; so will I multiply the seed of David my servant, and the Levites who minister to me.