stab (someone or something) in (something)
To pierce a person or animal in some particular part of the body (with some sharp, pointed implement). The attacker stabbed her in the leg and then ran off with her purse. The lion pounced on me, but I managed to stab it in chest before it could overpower me.
stab someone in something
to stab someone in a particular place. Max stabbed a prison guard in the belly and left him to die. Tom stabbed himself in the thigh by accident.