Numeric Custom validation Message in Laravel 5.2

I am writing the following code server side to validate if the role is selected or not ...

public function rules()
{
    return [
        'RoleID' => 'required|integer|min:1',
    ];
}

public function messages() {
    return [
        'User.RoleID'  => 'Please select role.',
    ];
}

Current Message

The role i d must be at least 1.

Expected Message

Please select role.

Can you please guide me to right path?

via Chebli Mohamed