Say you are my sister, that it may go well with me because of you, and that my life may be spared for your sake. – Abraham, Genesis 12:13
I just needed to hear that in the reverse, that Sarah should tell the Egyptians that Abraham is her brother, for it to click: a brother would be able to protect her. As the elder brother, he would own Sarah, be responsible for her. The Egyptians would need to deal with him to make any legal agreement involving her, so if he was known as her brother, he wouldn’t be murdered–he’d be honored and treated well, and he’d be able to stop anyone from making a deal to take Sarah. They would need him alive. In Sarah’s situation, a live brother is worth more than a dead husband.
I missed that whole idea before, which is ironic since I am so keen on women being treated as (Torah-respected) property. I thought Abraham was hiding behind Sarah, throwing her to the dogs. Not so. He was trying his best to protect her.