I was cutting through drywall and accidentally sliced one of the wires in the wall going from outlet to outlet. I turned off the power and I am going to have an electrician friend replace it for me. I wanted to buy the wire before he came to replace it but I am not sure what type to get. I don't really know too much about wiring so I don't know what other details to provide. Anyone know what type of wire I would need? Thanks.

Cut a foot of it off and take it to the hardware store. It's probably 14/2 or 12/2 with ground, Romex or NM-B cable.