It came about that
"And so." This phrase is used here to mark a new event in the story. (See: rc://en/ta/man/translate/writing-newevent)
"Joseph's master." This refers to Potiphar. This information can be made explicit. AT: "Joseph's master, Potiphar" (See: rc://en/ta/man/translate/figs-explicit)
heard the explanation his wife told him
"heard his wife explain to him." The word "his" and "him" here refer to Potiphar.
he became very angry
"Potiphar became very angry"
the place where the king's prisoners were confined
This can be stated in active form. AT: "the place where the king put his prisoners" (See: rc://en/ta/man/translate/figs-activepassive)
He was there
"Joseph stayed there"