【Incite】 , 【instigate】 ,  【abet】 ,  【foment】  are comparable when they mean to spur on to action or to excite into activity.

【Incite】 stresses stirring up and urging on; frequently it implies active prompting.

【Instigate】 , in contrast with  【incite】 , unequivocally implies prompting and responsibility for the initiation of the action; it also commonly connotes underhandedness and evil intention; thus, one may be incited but not instigated to the performance of a good act; one may be incited or instigated to the commission of a crime.

【Abet】 tends to lose its original implication of baiting or hounding on and to emphasize its acquired implications of seconding, supporting, and encouraging.

【Foment】  stresses persistence in goading; thus, one who incites rebellion may provide only the initial stimulus; one who foments rebellion keeps the rebellious spirit alive by supplying fresh incitements.