If your friend's VA pension is compensationfor a service-connected disability, the inheritance has no affect on his disability pension. A service connected disability compensation award is made by guidelines that determine a veteran's conditions and the resulting degree of disability incurred during active duty military service (or if preexisting was aggravated by the service). Cash in the form of inheritances, gambling winnings, the sale of property or other income that isn't the result of substantial gainful employment have no effect on service-connected disability compensation awards.
If the pension he receives is factored on income and net worth, such as a Non-Service Connected pension, and the inheritance amount was large enough it could cause a reduction or discontinuance of his benefit if it caused his net worth to become what the VA might consider excessive. The VA asset ceiling is 80K for such assets as bank accounts, stocks, bonds, mutual funds and any property other than the veteran's residence.
Only changes in assets that would have a substantial affect on the award or income that is not sporadic and/or minimal isolated event need to be reported when they occur. Otherwise this amount would be included in his next annual eligibility verification report that details all income,assets, and out of pocket medical expenses for the coming calendar year.