Mo. Rev. Stat. § 442.310: Certificate of proof, when granted.

No certificate of any such proof shall be granted, unless at least two credible witnesses shall state, on oath or affirmation, that they personally knew the person whose name is subscribed thereto as a party, well know his signature, stating their means of knowledge, and believe the name of the person subscribed thereto as a party was subscribed by such person; nor unless at least two credible witnesses shall, in like manner, state that they personally knew the person whose name is subscribed in such instrument as a witness, well knew his signature, stating their means of knowledge, and believe the name subscribed thereto as a witness was thereto subscribed by such person.