give custom field name in laravel form validation error message
$this->validate([ // 1st array is field rules
'userid' =>'required|min:3|max:100',
'username' =>'required|min:3',
'password' =>'required|max:15|confirmed',
], [ // 2nd array is the rules custom message
'required' => 'The :attribute field is mandatory.'
], [ // 3rd array is the fields custom name
'userid' => 'User ID'
]);