58:8 snail which melteth. This seems to be a reference to the slimy substance secreted by Palestinian snails as they crawl along the ground, thus apparently melting away, eventually leaving empty shells.
Psalm 59 (title). The reference in the title is probably to I Samuel 19:11, when Saul sent “messengers” to kill David in his own home and he was able to escape with the help of Michal, his wife. This is considered to be another (like Psalm 58) of the imprecatory psalms.