The credit of a witness may be impeached in the following ways by the adverse party, or, with the consent of the Court, by the party who calls him:––

   (1)  By the evidence of persons who testify that they, from their knowledge of the witness, believe him to be unworthy of credit;

   (2)  By proof that the witness has been bribed, or has ¹[accepted] the offer of a bribe, or has received any other corrupt inducement to give his evidence;

   (3)  By proof of former statements inconsistent with any part of his evidence which is liable to be contradicted;

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   Explanation. –– A witness declaring another witness to be unworthy of credit may not, upon his examination-in-chief, give reasons for his belief, but he may be asked his reasons in cross-examination, and the answers which he gives cannot be contradicted, though, if they are false, he may afterwards be charged with giving false evidence.

Illustration.

   (a)  A sues B for the price of goods sold and delivered to B. C says that he delivered the goods to B.

   Evidence is offered to show that, on a previous occasion, he said that he had not delivered goods to B. The evidence is admissible.

   (b)  A is indicted for the murder of B.

   C says that B, when dying, declared that A had given B the wound of which he died.

   Evidence is offered to show that, on a previous occasion, C said that the wound was not given by A or in his presence.

   The evidence is admissible.