Tex. Est. Code § 301.155
A fact contained in an application for issuance of letters testamentary or of administration or any other fact required to be proved by this subchapter may be proved by the sworn testimony of a witness with personal knowledge of the fact that is:
Added by Acts 2013, 83rd Leg., R.S., Ch. 1136 (H.B. 2912), Sec. 34, eff. January 1, 2014.