石けんで手を洗いなさい。

soap

indicates location of action; at; in; indicates time of action; indicates means of action; cause of effect; by; and then; so; indicates continuing action; indicates certainty, emphasis, etc.

hand; arm; forepaw; foreleg; handle; hand; worker; help; trouble; care; effort; means; way; trick; move; technique; workmanship; hand; handwriting; kind; type; sort; one's hands; one's possession; ability to cope; hand (of cards); direction; move (in go, shogi, etc.)

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

to wash; to investigate

to do