Inaction, negligence.
"It is the iron's own rust that destroys it: it is the sinner's own acts that bring him to hell. Disuse is the rust of mantras; laziness the rust of households; sloth is the rust of beauty; neglect is the watcher's ruin." - Buddha, Dhammapada
One of the seven capital sins. Must be transmuted into its pure form: diligence or zeal, which is related to Mercury (Raphael).
“The atoms of laziness are a serious obstacle for the progress towards the superior worlds.” - Samael Aun Weor, The Manual of Practical Magic