N.C. Gen. Stat. § 8C-1, Rule 602: Lack of personal knowledge.

A witness may not testify to a matter unless evidence is introduced sufficient to support a finding that he has personal knowledge of the matter. Evidence to prove personal knowledge may, but need not, consist of the testimony of the witness himself. This rule is subject to the provisions of Rule 703, relating to opinion testimony by expert witnesses. (1983, c. 701, s. 1.)