Commentary for II Samuel 20:22

The woman came [and spoke] to all the people. It is taught in a Tosefta:⁹Terumos 7:23. "She said to them, 'Since both he will be killed and they will be killed [they should] hand him over to them.¹⁰To Yoav’s men. If he were able to be saved, for example he was inside and you were on the outside and you were in mortal danger [fighting Yoav] [but] he could escape¹¹While you would be fighting. [then we have a rule that] it is prohibited to let one person be killed in order to save another, [therefore, you cannot] have him killed to save yourselves. But now that he is [anyway] going to be killed with you because the walls have been breached and there is no possibility of escape,¹²For anyone. [then] it is better that he alone die and you should not die along with him.' Rebbe Shimon said, this is what she said to them, 'Anyone who has rebelled against the kingdom of the House of Dovid is punishable by death.'¹³Threfore Shevah must be killed in order for you to be spared.