It is narrated from Sayyiduna Anas bin Malik (may Allah be pleased with him) that Abu Talhah (may Allah be pleased with him) proposed marriage to Umm Sulaym (may Allah be pleased with her) before he accepted Islam. She said: I do have an interest in you, and a man like you is not turned down, but you are a disbeliever and I am a Muslim woman. If you accept Islam, that will be my dowry (mahr); I will not ask you for anything else. So Abu Talhah (may Allah be pleased with him) accepted Islam and married her.
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 4660