Abraham tells king Abimelech that Sarah is his sister (Genesis 20:1 – 20:18)
Abraham moved his family, likely in search of better pastures for his herds, to Negev (located between Kadesh and Shur). From Negev he moved to Gerar where he lived for quite some time. Once again, Abraham and Sarah (his wife) told everyone that Sarah was his sister (see here for the first time he told