If someone got sliced by a knife (lightly— not deep) in the stomach, I know they’d get stitches, but would they be able to move around the next day or would it take a couple of days or more? If so, I’d better move that slicing injury. The slice did not go through the muscle.
If the cut doesn’t go into the muscle, the character should be fine getting stitches and then being able to move. It might be mildly sore, but not crippling by any means.
Keep in mind, depending on the size of the wound, a lot of movement can pop stitches. If he’s doing a lot of strenuous activity, and the wound is large, even if it doesn’t go through the muscle, the movement could pop the stitches and open the wound.
Also, any wound, even stitched close, is at risk for infection. Could be another complicating factor for your character.