Midrash su Isaia 44:16

The second trial was when he was put into prison for ten years—three years in Kuthi, seven years in Budri. After ten years they sent and brought him forth and cast him into the furnace of fire, and the King of Glory put forth His right hand and delivered him from the furnace of fire, as it is said, "And he said to him, I am the Lord who brought thee out of the furnace of the Chaldees" (Gen. 15:7). Another verse (says), "Thou art the Lord the God, who didst choose Abram, and broughtest him forth out of the furnace of the Chaldees" (Neh. 9:7).