Halakhah zu Schemot 20:6

And the Sages, may their memory be blessed, learned the matter that we are killed [rather than transgress] sexual immorality (Sanhedrin 74a), because the betrothed maiden is compared [by the Torah] to a murderer: Just as a murderer should be killed and not transgress, as we said; so too must a man be killed and not have intercourse with her. As the Torah does not tell metaphors for nothing, but only to teach a matter. They also had support from the tradition, which is an iron wall for all of their words. And the early authorities (rishonim) wrote that we only say a person must be killed and not transgress [about] transgressing a sin. But to not perform a commandment, he should transgress and not be killed, and not perform the commandment. And [it is] similar to what they, may their memory be blessed, said about Esther (Sanhedrin 74b), "She was ground of the earth" - meaning, it was similar to [a situation of] 'sit and do not act,' as behold a woman has intercourse against her will. And even if the woman assisted in the intercourse after her impulse covered her, she is not liable with this - as there is no greater coercion than this. And that which we find stories about the early pious ones that were killed even [so that they not participate in] the negation of a [positive] commandment - and similar to what they, may their memory be blessed, said (Mekhilta d'Rabbi Yishmael 20:6), "What is to you to go out to stoning? Because I circumcised my son. What is to you to go out to hanging? Because I took the lulav" - that was an [extra] measure of piety that they did and they saw that [their] generation needed this. And they were great sages fitting for this, to decide about this. As otherwise they would not have been permitted to give over their souls to die - as not everyone has permission to be killed for [other matters] than those that they, may their memory be blessed, obligated us about. Moreover, [such a person] would be liable for his life (Mishneh Torah, Foundations of the Torah 5:4).