Send ye the lamb to the ruler of the land; rather, the lamb of the ruler of the land—the lamb (or lambs, kar being used collectively) due to the ruler as a mark of subjection. In the time of Ahab Mesha had paid a tribute to Israel of a hundred thousand lambs and a hundred thousand rams annually (2 Kings 3:4).
The prophet recommends that this, or some similar, tribute should now be paid to the King of Judah instead. Israel having been absorbed into Assyria. From Sela. Either Moab is regarded as having taken refuge in Edom, and is therefore bidden to send her tribute from the Edomite capital, Sela (equivalent to "Petra"), or "Sela," here is not a proper name, but a collective used to designate the rocky parts of Moab, to which she had betaken herself (as in Jeremiah 48:28).
The latter supposition is, on the whole, the more probable. To the wilderness; literally, wildernesswards; i.e. by the way of the wilderness. The enemy being regarded as in possession of the northern end of the Dead Sea, Moab is recommended to send her tribute round the southern end, and so by way of "the wilderness of Judah," to Jerusalem.