לָכֵן laken "therefore" a connecting particle, marking a logical link or a conclusion drawn from evidence presented. Commonly used to link the judgment to the accusation in oracles of judgment (Am 4:12; 5:11, 13?; 6:7).
In Amos (3:11;
5:16; 7:17) as in other prophets it sometimes introduces
the (introductory) messenger formula "thus says..."
in these cases presumably the oracle itself is a consequence of
what goes before.