"and Him shall you fear": His awe shall be upon you.
"and His mitzvoth shall you keep": This is a negative commandment.
"and His voice shall you heed": the voice of His prophets.
"and Him shall you serve": Serve Him in His Temple.
"and to Him shall you cleave": Separate yourselves from idolatry and cleave to the L-rd.
(Devarim 13:6) "And that prophet": and not one who is under compulsion.