What type of bearing? What environment, sealed or unsealed, etc.
It is very desirable to achieve EHD "ElastoHydroDynamic" lubrication in ball and roller bearings for best life.
To achieve EHD requires some minimum bearing speed and minimum lubricant (base oil in grease) viscosity at working temperature.
No idea if vaseline has a base oil, or its viscosity. I can;t picture it being very effective as a bearing lubricant.