Joseph says what he knows will be telling to Pharoah, that he has sworn to his father to do something for him, and he must now carry out his word. Pharoah has only even known Joseph to be a man of integrity who never exaggerates, never breaks his word.
Pharaoh wants to be involved. Why? Because Joseph is the Saviour of Egypt. Perhaps this Pharoah even became a believer in the true God through Joseph’s witness and his message. Pharaoh gives his consent and has taken note of Joseph’s oath. He agrees that it is important to honour this. A wise ruler wants integrity and honesty in his kingdom, and this comes by example, so that it must be seen to come down from the ruler. Many expect their people to follow an example that they do not set, but they know little about human nature. The people conclude that the rulers require integrity for their own convenience, but that they give themselves liberty to break their own rules. They are therefore deeply impressed when they know a man exercises integrity even when it costs him personally.