delivered the opinion of the court.

Appellant was convicted on a charge of the murder of Den-ton W. Odell. On the trial, Mrs. Grace Odell, the widow of the slain man and the sister of the slayer, was a witness for the defendant. She and two negro women were the .only witnesses at the actual scene of the conflict, which resulted in the death of Odell and the almost fatal wounding of Jeffries. On cross-examination by the state’s attorney she was asked whether, in a conversation with Mrs. Josie Mauldin the day after the killing, she had not, after picking up a Bible and opening it, said: “Here is the chapter Denton read last night, and prayed beautifully for Paul.” The court allowed this question over objection, which ruling was clearly erroneous, and *761afterwards allowed Mrs. Mauldin to contradict her, and tbis ruling tvas error. Williams v. State, 73 Miss., 830, and the authorities there cited.

Under all the facts in tbis case, which we do not stop now to recite, this error is of itself fatal, and was incurable. It gave to the state a tremendous leverage in the mind of the average juror on a matter absolutely immaterial. This evidence was confessedly incompetent as original testimony to show guilt, and witnesses may not be contradicted as to their own statements on matters immaterial.

The court granted the third instruction asked by the state, which charged tb.e jury that “if they believe from the evidence that any witness has wilfully sworn falsely to any material matter in this case, or that the testimony of such witness is unreasonable, or that the testimony of any witness is colored or biased on account of relationship of the witness to the defendant, or if from any reason arising out of the evidence they may believe the testimony of any witness is untrue, then they may disregard the whole testimony of such witness, if they see proper to do so.” It was error to give this charge. The dis-junctives make it erroneous. Finley v. Hunt, 56 Miss., 221; Railroad Co. v. Herrick, 62 Miss., 28. It was manifestly aimed at Mrs. Odell, and was, under the facts of this case, tantamount to telling the jury to disbelieve her.

The sixth instruction asked by the state, and given, is erroneous. It charges the jury that “while it is true they are not authorized to convict unless from all the evidence they believe beyond every reasonable doubt that Jeffries is guilty, still this does not mean that they must know he is guilty, for mathematical certainty is not required in any case, but if they, from a full and fair comparison of all the evidence in the case, believe he is guilty, then this is sufficient, and yo-u should convict him.”

The last clause in this charge is put as the conclusion from an attempted definition of reasonable doubt, and reduces it to *762a mere matter of belief, and is fatal error, and such error as is not susceptible of cure, from the very fact that it is given as the result of reasoning on what is a reasonable doubt. Brown v. State, 72 Miss., 95; Burt v. State, 72 Miss., 410; Webb v. State, 73 Miss., 456-460; Lipscomb v. State, 75 Miss., 560-577; Powers v. State, 74 Miss., 779.

Reversed and remanded.