Then Abimelech called Abraham and said to him, “What have you done to us? And how have I sinned against you, that you have brought on me and my kingdom a great sin? You have done to me things that ought not to be done.” – Genesis 20:9
Even the light of nature teaches men that the sin of adultery is a very great sin: be it observed, to the shame of many who call themselves Christians, and yet make a light matter of it. Matthew Henry.