addRuleMessage('startsWithNumber', 'The {field} must start with a number.'); $v->addRule('startsWithNumber', function($value, $input, $args) { $value = trim($value); return is_numeric($value[0]); }); $v->validate([ 'username' => ['dale', 'required|min(3)|max(20)|startsWithNumber'] ]); if ($v->passes()) { // Passed } else { var_dump($v->errors()->all()); }