Hazrat Sha'bi (may Allah have mercy on him) said: "If the husband and wife disagree about the dowry, the husband's statement will be accepted with an oath, and the woman will be required to provide evidence." Shaibani said: "According to the statement of Ibrahim (may Allah have mercy on him), the woman's statement will be accepted if it is in accordance with the customary dowry."
Hadith Referenceسنن سعید بن منصور / كتاب الطلاق / 3290