system/Validation/Validation.php
public function setRuleGroup(string $group)
	{
		$rules       = $this->getRuleGroup($group);
		$this->rules = $rules;

		$errorName = $group . '_errors';
		if (isset($this->config->$errorName))
		{
			$this->customErrors = $this->config->$errorName;
		}
	}
public function setRuleGroup(string $group)
	{
		$rules       = $this->getRuleGroup($group);
		$this->rules = $rules;

		$errorName = $group . '_errors';
		if (isset($this->config->$errorName))
		{
			$this->customErrors = $this->config->$errorName;
		}
	}
Set rule group.

@param string $group Group.

@throws \InvalidArgumentException If group not found.