"This will required, to be valid, three attesting witnesses. Joseph Kolb, the testator, died in June, 1880. The [Mississippi] Revised Code of 1871, therefore, governs. Section 2388 of that Code provides as follows: 'If not wholly written and subscribed by himself or herself [the will] shall be attested by three credible witnesses in case of the devise of real estate.' The word 'credible,' in this statute, is synonymous with 'competent.'
"[S]ince the statute required, when this will was made, three competent witnesses to a will devising land, and since a subscribing witness to whom a devise was made by that will was not competent because of his interest, the whole will [fails]."
"[I]t is a rule of substantive law [under the Mississippi Revised Code of 1871], and not a rule of evidence, that the written attestation of three competent witnesses to the will shall be essential to its validity; that is to say, this written attestation of three competent witnesses is, by the substantive law, made a solemn formality without the observance of which the will was absolutely void in its entirety . . . ."