No trustee, unless expressly authorized by the trust instrument, shall directly or indirectly lease, buy or sell any property for the trust from or to itself or an affiliate; or from or to a director, officer, or employee of such trustee or of an affiliate; or from or to a relative, employer, partner, or other business associate. Notwithstanding this provision or any statute to the contrary, a trustee may lease, purchase or sell property from or to the trust he represents as trustee if specifically authorized to do so in a decedent's will or the instrument creating the trustee relationship, including the establishment of a trust service office as provided by chapter 51A-5.
SDCL 55-4-13