"Please be careful." She can't move her hands to push his away while she concentrates on piecing his guts back together, but the look on her face strongly implies she'd rather like to. "I don't want to heal your hand underneath the skin of your stomach by accident."

His fingers aren't actually pushing into the wound, which is really the only way she'd actually have to worry about that, but she's never healed a wound this bad on anyone but herself before, and she's hyper-aware of everything that could possibly go wrong. Fortunately, it's already at the point where he'd have to quite deliberately stick his fingers inside himself to cause much of a problem.