Smell the crankcase for the presence of gasoline in the oil.

and if so, drain/replace crankcase oil ASAP. Such contaminated with raw fuel does not provide engine lube protection. Fix source of leaking fuel (usually carb) - also good idea to install manual fuel shutoff valve between tank and carb & use same to run engine dry each time just before putting machine away.

Yeah there was gasoline in the crankcase just not sure where it's coming from. My dad's gonna have one of his friends come look at it to see if they know how to fix it. Would this also cause the exhaust to get extremely hot and start smoking because that is what happened after you clean out the gasoline and restart the mower?

The carb needle & seat is leaking.
While the engine is off, gas seeps through, into the cylinder, past the rings and into the crank case.

This thins the oil which, when the engine is running, easily goes past the rings (because it's so thin) and burns in the combustion chamber, producing lots of whitish smoke.
Oil residue tends to collect in the muffler and will take some time to burn out. You are probably burning some of this excess IN the muffler, since the fuel/oil/air mixture will be overly rich.

After fixing the carb, MAKE SURE you change the oil. Gasoline is NOT a good lubricant!

Thanks for your help

Thanks for your help