Nazir, Chapter 6, Mishnah 4. This mishnah addresses the question of how many sets of lashes a person can incur for multiple violations of the laws of nezirus.
The Principle of Hasra'ah (Warning):
To be liable for lashes, a warning is required - a verbal caution delivered by witnesses not to commit the transgression. This is the principle upon which the mishnah is built: a nazir who violated his nezirus many times but was warned only once is liable for only one set of lashes; but if he was warned before each and every act, each act counts as a separate transgression, and he is therefore liable to lashes for each one on its own.
The Three Cases in the Mishnah:
"Nazir shehayah shoseh yayin kol hayom - eino chayav ela achas" - a nazir who was drinking wine all day is liable to only one set of lashes. Drinking wine is of course forbidden to him, but since he received only one warning, he is liable to only one set of lashes for all his drinking. However, "amru lo: al tishteh, al tishteh, vehu shoseh - chayav al kol achas ve'achas" - when they warn him each and every time not to drink and he drinks after the warning, there is a separate transgression and a separate punishment for each and every drink.
"Hayah megale'ach kol hayom - eino chayav ela achas" - a nazir who violates his nezirus by cutting his hair all day is liable only once if he received only one warning. However, "amru lo: al tegale'ach, al tegale'ach, vehu megale'ach - chayav al kol achas ve'achas" - when they warn him before each act not to shave or cut his hair, and he goes on cutting after each warning, he is liable separately for each and every time.
"Hayah mitamei lemeis kol hayom - eino chayav ela achas" - a nazir who was becoming tamei through contact with a corpse all day is liable only once. However, "amru lo: al titamei, al titamei, vehu mitamei - chayav al kol achas ve'achas" - each time they warned him not to become tamei and he came into contact with the corpse again, he is liable to a separate set of lashes for each and every time.
In summary: this mishnah establishes that the number of sets of lashes is determined not by the number of transgressive acts alone, but by the number of warnings. In all three prohibitions of nezirus - drinking wine, cutting hair, and becoming tamei through a corpse - one who transgresses all day with a single warning is liable only once, whereas one who is warned before each act is liable for each and every one.