WritingLaw (Page 273)

115. Estoppel.
When one person has by his declaration, act or omission, intentionally caused or permitted another person to believe a thing to be true and to act upon such belief, neither he nor his representative shall be allowed, in any suit or proceeding between himself and such person or his representative, to deny the truth of that thing.

Illustration-
A intentionally and falsely leads B to believe that certain land belongs to A, and thereby induces B to buy and pay for it.Read…

Witnesses. 118. Who may testify?
All persons shall be competent to testify unless the Court considers that they are prevented from understanding the question put to them, or from giving rational answer to those questions, by tender years, extreme old age, disease, whether of body and mind, or any other cause of the same kind. 

Explanation-
A lunatic is not incompetent to testify, unless he is prevented by his lunacy from understanding the questions put to him and giving rational answers to them.Read…

The Examination of Witnesses. 135. Order of production and examination of witness.
The order in which witness are produced and examined shall be regulated by the law and practice for the time being relating to civil and criminal procedure respectively, and in the absence of any such law, by the discretion of the Court.

136. Judge to decide as to admissibility of evidence.
When either party proposes to give evidence of any fact, the Judge may ask the party proposing to give the evidence in what manner the alleged fact, if proved, would be relevant; and the Judge shall admit the evidence if he thinks that the fact, if proved, would be relevant, and not otherwise.Read…

147. When witness to be compelled to answer.
If any such question relates to a matter relevant to the suit or proceeding the provisions of Section 132 shall apply thereto.

148. Court to decide when question shall be asked and when witness compelled to answer.
If any such question relates to matter not relevant to the suit or proceeding, except in so far it affects the credit of the witness by injuring his character, the Court shall decide whether or not the witness shall be compelled to answer it and may, if it thinks fit, warn the witness that he is not obliged to answer it. In exercising its discretion the Court shall have regard to the following considerations-

(1) Such questions are proper if they areRead…

Refreshing Memory. 157. Former statements of witness may be proved to corroborate later testimony as to same fact.
In order to corroborate the testimony of a witness, any former statement made by such witness relating to the same fact, at or about the time when the fact took place, or before any authority legally competent to investigate the fact, may be proved.

158. What matters may be proved in connection with proved statement relevant under Section 32 or 33.Read…

167. No new trail for improper admission or rejection of evidence.
The improper admission or rejection of evidence shall not be ground of itself for a new trail or reversal of any decision in any case, if it shall appear to the Court before which such objection is raised that, independently of the evidence objected to and admitted, there was sufficient evidence to justify the decision, or that, if the rejected evidence had been received, it ought not to have varied the decision.Read…