fire under

*fire under someone

Fig. something that makes someone start doing something. (*Typically: build ~; light ~; start ~.) The teacher built a fire under the students, and they really started working. You had better light a fire under your staff. Either that or we will lay off some of them.
See also: fire
References in classic literature ?
It seems that each green warrior has certain objective points for his fire under relatively identical circumstances of warfare.
A fire under those conditions could be extremely fast-moving,'' said Capt.