Assyria can't save us. We won't ride on horses; Neither will we say any more to the work of our hands, 'Our gods!' For in you the fatherless finds mercy."
There are some further strong suggestions of the New Covenant in this verse: (1) the projected abandonment of idolatry, and (2) the mercy extended to the fatherless, perhaps a prophecy of the adoption of the Gentiles into the kingdom of God after Pentecost.  In fact, the rejection of the reliance upon secular states may also be viewed as an ear-mark of Christianity, making three witnesses of the New Covenant in this single verse.  We shall note each of them: