Abraham was instructed by God to refer to his wife, Sarah, as his sister (Abraham 2:22-25). This takes advantage of an ambiguity in the Egyptian language: the Egyptian word for wife (hime) means only wife, but the Egyptian word for sister (sone) means both sister and wife. Thus, the term that Abraham used was not false, but ambiguous. It was also necessary: since numerous Egyptian texts discuss how pharaohs could take any woman that they fancied and would put the husband to death if the woman was married, this advice saved Abraham’s life.
God was willing to save Abraham’s life on more than one occasion. Doing so fulfilled part of the covenant that God had made with him. (John Gee. An Introduction to the Book of Abraham [Provo, Utah: Religious Studies Centre, Brigham Young University, 2017], 102, italics in original)