(a) Al-Hasan al-Basri (may Allah have mercy on him) narrates from Sayyiduna Ali (may Allah be pleased with him) that he led the eclipse prayer with five bowings and four prostrations.
(b) It is mentioned from Sayyiduna Ali (may Allah be pleased with him) that he performed four bowings in each rak'ah.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب صلاة الخسوف / 6327