Imam al-Shafi'i (may Allah have mercy on him) says: They narrated something on this from Sayyiduna Ali (may Allah be pleased with him), the like of which is not established even if no one else had contradicted it: that there can be no dowry less than ten dirhams.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصداق / 14387