‘They are enclosed in their own fat (midriff?),
With their mouth they speak proudly.
They have now encompassed us in our steps,
They set their eyes to cast us down to the earth.'
It may be that he vividly picture his enemies as being entrapped in their own midriff. (Different parts of the body are often used to depict the whole person and as thus affecting behaviour). Thus they are unable to consider their ways or behave humanely. The fat blocks their ears. Or it may signify that in their current prosperity (possibly gained by toadying up to the psalmist's enemy) they are unable to hear the voice of God and behave righteously. Thus when they speak it is always with pride and arrogance. Either way they have now trapped the psalmist and his men, with their eyes showing their determination to cast them down to the earth.