I hit his mouth and use very serious tone to told him, " you are naughty, you don't bit mami" and repeat it. he sometimes smile at me (think I was playing with him), but I just look at him and use serious tone to told him again, "you don't mami, it hurts".
if he continues, I will stop feed him for 2-3 mins as penalty. but give him something to bite coz he may be teething.