Sayyiduna Anas (may Allah be pleased with him) relates: Abu Talhah (may Allah be pleased with him) proposed marriage to Umm Sulaym (may Allah be pleased with her) before he accepted Islam, and she said: "I do indeed desire you, and a man like you is not turned away, 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 besides it." So Abu Talhah (may Allah be pleased with him) married her.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 21735