If a juror have any personal knowledge respecting a fact in controversy in a cause he must declare it in open court during the trial. If, during the retirement of a jury, a juror declare a fact, which could be evidence in the cause, as of his own knowledge, the jury must return into court. In either of these cases, the juror making the statement must be sworn as a witness and examined in the presence of the parties. R.L.1910, § 5898.
Oklahoma Legal Code