Abdullah bin Abi Talhah said that Abu Talhah (may Allah be pleased with him) married Umm Sulaym (may Allah be pleased with her), and the dowry between them was Islam. Umm Sulaym (may Allah be pleased with her) had accepted Islam before Abu Talhah. When he proposed to her, she said: I have accepted Islam; if you accept Islam, I will marry you. So he accepted Islam, and the dowry between them was Islam itself.
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 4661