Imam Ahmad bin Hanbal (may Allah have mercy on him) says: Ghiyath bin Ibrahim prompted Dawud al-Awdi (to say) that al-Sha'bi narrates from Sayyiduna Ali (may Allah be pleased with him) that the dowry should not be less than ten dirhams, and so it became a hadith.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصداق / 14389