Section 3. It shall be unlawful for any person, company, association, or corporation to require of its servants or employees as a condition of their employment, or otherwise, any contract or agreement whereby such person, company, association, or corporation shall be released or discharged from liability or responsibility on account of personal injuries which may be received by such servants or employees while in the service or employment of such person, company, association, or corporation, by reason of the negligence of such person, company, association, corporation, or the agents or employees thereof; and any such contract or agreement if made, shall be null and void.