Commentaire sur La Genèse 34:17

ולקחנו את בתנו, even though she is at this point in time locked up in your house we will liberate her from you.

ואם לא תשמעו, "If you are not agreeable, etc." This was also a clever move. They did not threaten retaliatory action for the rape of their sister but only told Chamor that in that case they would take their sister and leave the region. They made it clear that they did feel insulted and that therefore they could not consider remaining in a region where rape went unopposed. On the other hand, if the people were to circumcise themselves en masse this would show a change of heart on their part towards the laws of sexual purity. It was the brothers' astuteness that caused Chamor to tell his people that the family of Jacob were sincere (verse 21).

ואם לא...בתנו, as we explained on 34,9

ולקחנו את בתינו, “we will take our houses, etc.” They did not threaten to liberate their sister by force. The reason they did not was because they were speaking on behalf of their father.

We will take our daughter and go. Since Shechem was unaware that relations with the uncircumcised was a disgrace to them, there was nothing to avenge. With this answer they accomplished three things: 1) They concealed their desire for revenge. 2) They convinced him that circumcision was the only way to acquire Deenah. 3) They gave the impression that if everyone were circumcised they would stay.

והלכנו, with all our wealth which you would otherwise benefit from.

The brothers also intended to speed up a decision by Chamor and Shechem personally when they held out the prospect of "we will take our daughter and leave." Perhaps Chamor thought that as soon as Dinah would be removed from the region the brothers would prepare to take their revenge.