When an estate is being probated, or a minor or incompetent person has a legal guardian, the administrator or executor of the estate, or guardian of the minor or incompetent person, shall have the authority to execute all instruments of conveyance provided for in this chapter on behalf of the estate, minor or incompetent person without other proceedings than approval by the judge of the district court endorsed on the instrument of conveyance. Competent evidence to prove that reasonable compensation is being paid for the execution of said instrument shall be presented to the court prior to said approval.