Nafi' (may Allah have mercy on him) says: A man came to Ibn Umar (may Allah be pleased with them both) and said that he had separated from his wife. Ibn Umar (may Allah be pleased with them both) said: Give her such-and-such an amount and clothe her with such-and-such. We calculated it, and it came to about thirty dirhams. I said to Nafi' (may Allah have mercy on him): What was this man like? He said: He was a man of moderate means.
(b) Through another chain, Nafi' (may Allah have mercy on him) narrates from Ibn Umar (may Allah be pleased with them both): The least provision (mut'ah) is thirty dirhams.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصداق / 14406