It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that on the day of Badr the Messenger of Allah (peace and blessings be upon him) fixed the ransom for the people of the Jahiliyyah at four hundred.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 12846