In Gen. 26:6-11, we find Isaac in the land of Gerar, still commanded by King Abimelech. And, in a stunning case of deja-vu, Isaac tells his wife Rebekah to pose as his sister. But Abimelech has begun to catch on to this ploy: even before his family becomes barren and God must intervene in a dream (as happened before, when Abraham pulled the same stunt, Gen. 20:1-18), Abimelech puzzles out the deception and commands his men not to touch Isaac or his wife.
What was that phrase? "Fool me once, shame on you. Fool me twice, shame on me." At least Abimelech learns from his mistakes.