Like getting blood out of/from a stone
Definition 1 of 1
Pro Tip 1/3Resistance Implied
The phrase often suggests someone's reluctance or refusal to provide what is being asked for. 
Asking her for a favor is like getting blood out of a stone.
Pro Tip 2/3Metaphorical Use
This phrase is never used literally. It's always a metaphor for difficult tasks or situations. 
Completing this project on time feels like getting blood from a stone.
Pro Tip 3/3Negative Emotion
Using this phrase can express frustration or exasperation with the difficulty of the task. 
Getting him to admit his mistake was like getting blood from a stone.