Section five shall not prohibit the following:
No employee engaged in work subject to the provisions of this clause shall be required to perform such work, and refusal to work for any retail establishment on Sunday shall not be grounds for discrimination, dismissal, discharge, reduction in hours, or any other penalty. The provisions of this paragraph shall be enforced by the office of the attorney general. The provisions of section one hundred and eighty A of chapter one hundred and forty-nine shall apply to any violation of this paragraph.
Mass. Gen. Laws ch. 136, § 6