Wiktionary
lift a finger
vb. 1 (&lit lift finger English) 2 (context idiomatic English) To make minimal effort; to help as little as possible.
Usage examples of "lift a finger".
Deety, it's the hardest work possible even if you don't lift a finger.
They wouldn't even lift a finger to save their own grandmothers from the Ravenous Bugblatter Beast of Traal without orders signed in triplicate, sent in, sent back, queried, lost, found, subjected to public inquiry, lost again, and finally buried in soft peat and recycled as firelighters.
I could walk out of Sanction, Silvanoshei said to himself, and no one would lift a finger to stop me.