Validation issues in Laravel

I am writing the following code to validate the first and last name in Request class.

public function rules()
{
    return [
        'FirstName'             => 'max:30',
        'FirstName.regex'       => 'regex:/^[a-zA-Z]+$/',
        'LastName'              => 'required|min:3|max:30',
        'LastName.regex'        => 'regex:/^[a-zA-Z]+$/',
    ];
}

public function messages () {
    return [
        'FirstName.regex'       => 'FirstName can have only chars and numbers.',
        'LastName.regex'        => 'LastName can have only chars and numbers.',
    ];
}

If I input FirstName or LastName as Pankaj Garg It's being accepted.

Can u guide, where I am missing the correct code?

via Chebli Mohamed