Tenn. Code Ann. § 23-3-106: Testimony as to interests transferred pending action

No attorney, solicitor or other person, under the pretext of having transferred an interest in real estate, obligations for the performance of contracts or notes for money, during the pendency of any suit at law, shall be permitted to give testimony in favor of those who held a joint interest with the attorney, solicitor or other person at the commencement of such suits, or by which the attorney, solicitor or other person would be released from any liability to perform contracts or pay money.