lift a hand
To help with something. Often used in the negative to indicate a lack of willingness to exert even the bare minimum of effort. I know you're watching TV, but can you perhaps lift a hand and help me bring in these grocery bags? I clean every weekend, and you never lift a hand to help!
lift a hand (against someone or something)
and raise a hand (against someone or something)Fig. to threaten (to strike) someone or something. (Often in the negative. The a hand can be replaced with one's hand.) She's very peaceful. She wouldn't lift a hand against a fly. Would you raise your hand against your own brother?