It is narrated from Sayyiduna Wa'il bin Hujr (may Allah be pleased with him) that he said: "In the time of the Messenger of Allah (peace and blessings be upon him) a woman was forced (into intercourse), so he (peace and blessings be upon him) waived the prescribed punishment (hadd) from her and carried out the prescribed punishment on the one who assaulted her, and it is not mentioned that he (peace and blessings be upon him) fixed a dowry (mahr) for her."
Hadith Referenceالمعجم الكبير للطبراني / باب الواو / 18284