Mo. Rev. Stat. § 526.040

Before any party shall be entitled to the injunction herein provided, he shall have filed in the circuit court, or in the office of the clerk thereof, having jurisdiction of the suit, his petition setting forth his cause of action; and when the injunction shall be granted by the circuit judge, it shall be in writing, signed by the judge, and returned together with the bond, to the office of the clerk of the circuit court wherein such petition shall have been filed, and become a part of the record in said cause.