From verse 13 the initiative in the negotiations passes to Jacob’s sons.

The sons of Jacob answered … deceitfully: answered is used here in the sense of “reply” or “respond to” Shechem’s generous offer in verse 12. Deceitfully is often expressed in figurative terms; for example, “to speak with two tongues,” “to cover the eyes with lies,” “to cause someone to take the wrong path.” We may translate with such a figure; for example, “The sons of Jacob spoke with two tongues when they replied to Shechem.”

Because he had defiled their sister Dinah: for defiled see verse 5. In some languages the reason clause must come before the result clause. In these cases we may translate verse 13, for example, “Shechem had caused Dinah to suffer shame, and so Jacob’s sons spoke with two tongues when they replied to Shechem and his father Hamor.” Since the speech of the brothers does not begin until the next verse, some translations focus the content of this verse on their thinking; for example, “The sons of Jacob were thinking about the bad thing that Shechem had done to their sister Dinah. So they made up their minds to deceive Shechem and his father Hamor, (14) and they said, ….”

Quoted with permission from Reyburn, William D. and Fry, Euan McG. A Handbook on Genesis. (UBS Helps for Translators). New York: UBS, 1997. For this and other handbooks for translators see here .