Jumper cables for power inverter?
You shall want to determine the quality of your jumper cables. Inexpensive jumper cables are going to be constructed poorly at the crimps and will certainly have smaller gauge wire than a more expensive, higher quality set.

Disregarding conversion loss internal to the inverter and using simple numbers, you could say that the inverter will draw 80 amperes at 12 volts to provide the 960 watts you specify. Even if those numbers are inaccurate, it's reasonable to believe that they will serve the purpose of this calculation.

A quick check with The Google shows that starting an automobile will draw 250 amperes and higher, depending on temperature and condition of the vehicle. This gives you a factor of 3 or better when considering if the cables will tolerate such current loads.

More information about jumper cables can be found on a sister site:
https://mechanics.stackexchange.com/questions/10985/how-do-i-determine-what-type-of-jumper-cable-i-should-carry

You would want to ensure you have a solid grip on both ends of the cable and watch them carefully for signs of heating. Testing the temperature of the connections with an IR non-contact thermometer, an IR camera accessory to your phone or even your hands on an insulated section will give you an indication of pending doom (or not.)

If your battery is flooded lead acid, eye protection and other suitable precautions are encouraged. Batteries explode when hydrogen gas is generated during charging, but not when discharging, reducing the danger for your project.