Mo. Rev. Stat. § 540.080: Oath of grand jurors.

Grand jurors may be sworn in the following form:

Do you solemnly swear you will diligently inquire and true presentment make, according to your charge, of all offenses against the laws of the state committed or triable in this county of which you have or can obtain legal evidence; the counsel of your state, your fellows and your own, you shall truly keep secret? You further swear that you will present no one for any hatred, malice or ill will; neither will you leave unpresented any one for love, fear, favor or affection, or for any reward or the hope or promise thereof, but that you will present things truly as they come to your knowledge, to the best of your understanding, according to the laws of this state, so help you God.