They have spoken words, swearing falsely in making a covenant: thus judgment springeth up as hemlock in the furrows of the field.
They have spoken words - mere empty words.
Swearing falsely in making a covenant - breaking their engagement to Shalmaneser (2 Kings 17:4), and making a covenant with So, though covenants with foreigners were forbidden.
Thus judgment springeth up as hemlock - i:e., divine judgment shall spring up as rank and as deadly as hemlock in the furrows (Deuteronomy 29:18, "Lest there should be among you a root that beareth gall and wormwood;" Amos 5:7; Amos 6:12, "Ye have turned judgment into gall, and the fruit of righteousness into hemlock"). Gesenius translates, 'poppy;' Grotius, 'darnel.'
In the furrows of the field. They broke up the furrows, preparing the soil deliberately for the cultivation of injustice (which is the only kind of judgment know): so they are ripe for the divine judgment.