βρι

From LSJ

σκληρόν σοι πρὸς κέντρα λακτίζειν → it is hard for thee to kick against the pricks, it is hard for you to kick against the goads

Source

Russian (Dvoretsky)

βρῐ: усилит. приставка со знач. весьма (напр., βριήπυος).