Is a false oath sworn after insistence upon the swearer considered an oath of immersion (yamin ghamus), and does sin result from it, and what is its expiation?

Swearing falsely is a 'Yamin (definition) Ghamus' (a perjurious oath that plunges the swearer into sin). The questioner's situation, when she asked her brother to swear an oath about his falsehood, is one of three scenarios:

1. She knew that the oath would deter him from his lie. In this case, she is not blameworthy because her purpose was to deter him or extract the truth from him. 2. She knew that he would persist in his lie and trivialise the oath. In this case, she is blameworthy and has caused this sin, and she must offer sincere repentance. 3. She was unaware of his reaction. In this case, she is not blameworthy, even if she exposed her brother to bearing this burden.

This applies if the subject of the conversation was important enough to warrant an oath. However, if there was no benefit from it, the questioner is blameworthy in any case, because the name of Allah should not be trivialised, nor should one swear frequently, even if speaking the truth. As Al-Shafi'i said: "I have never sworn an oath, neither truthfully nor falsely."

It is obligatory to advise the brother to abandon lying and the 'Yamin Ghamus'.