True or Lie Oath
Issue No. 2304- If a person swears that he is telling the truth, such an oath is disliked if what he says is true, and if it is a lie it is haram and of the major sins. However, if he is forced to swear in order to save himself or another Muslim from the mischief of an oppressor, there is no harm in it, and in fact, at times it becomes obligatory. This sort of oath which is meant to prove something is quite different from the oath which was discussed earlier and which was for the performance or abandonment of an act.