Albert Barnes Commentary 2 Samuel 13:12

"And she answered him, Nay, my brother, do not force me; for no such thing ought to be done in Israel: do not thou this folly." — 2 Samuel 13:12 (ASV)

Tamar’s words are a verbal quotation from Genesis 34:7. The natural inference is that Tamar knew this passage in Genesis and wished to profit from the warning it contained. (Compare to 2 Samuel 13:13.)