Note this first statement is very limited in scope, and the second gives great breadth.
"And thou shalt not command him who is at thy head, and at the head of the church; For I have given him the keys of the mysteries, and the revelations which are sealed, until I shall appoint unto them another in his stead."
"Behold, I say unto thee, Oliver, that it shall be given unto thee that thou shalt be heard by the church in all things whatsoever thou shalt teach them by the Comforter, concerning the revelations and commandments which I have given. But, behold, verily, verily, I say unto thee, no one shall be appointed to receive commandments and revelations in this church excepting my servant Joseph Smith, Jun., for he receiveth them even as Moses. And thou shalt be obedient unto the things which I shall give unto him, even as Aaron, to declare faithfully the commandments and the revelations, with power and authority unto the church. And if thou art led at any time by the Comforter to speak or teach, or at all times by the way of commandment unto the church, thou mayest do it. But thou shalt not write by way of commandment, but by wisdom;" (D&C 28:6-7, 1-5)