I stand corrected he did not tell him to lie, but to be deceitful Abraham 2:24
22 And it came to pass when I was come near to enter into Egypt, the Lord said unto me: Behold, Sarai, thy wife, is a very fair woman to look upon;
23 Therefore it shall come to pass, when the Egyptians shall see her, they will say—She is his wife; and they will kill you, but they will save her alive; therefore see that ye do on this wise:
24 Let her say unto the Egyptians, she is thy sister, and thy soul shall live.
25 And it came to pass that I, Abraham, told Sarai, my wife, all that the Lord had said unto me—Therefore say unto them, I pray thee, thou art my sister, that it may be well with me for thy sake, and my soul shall live because of thee.
22 And it came to pass when I was come near to enter into Egypt, the Lord said unto me: Behold, Sarai, thy wife, is a very fair woman to look upon;
23 Therefore it shall come to pass, when the Egyptians shall see her, they will say—She is his wife; and they will kill you, but they will save her alive; therefore see that ye do on this wise:
24 Let her say unto the Egyptians, she is thy sister, and thy soul shall live.
25 And it came to pass that I, Abraham, told Sarai, my wife, all that the Lord had said unto me—Therefore say unto them, I pray thee, thou art my sister, that it may be well with me for thy sake, and my soul shall live because of thee.
So saying they were brother and sister was not a lie.