Genesis 20:6

I know that thou didst not this knowingly and maliciously, but imprudently and inconsiderately, which is indeed an extenuation of thy sin, though not a total excuse. Compare 1 Kings 9:4 1 Chronicles 29:1. I also withheld thee, partly by my restraining grace, and partly by my powerful providence, and the plague mentioned Genesis 20:17. Which plainly shows that ignorance is not always an excuse for sin. See Luke 12:48. This sin, though directly committed against Abraham and Sarah only, is said to be against God, as other such sins are, Genesis 39:9 Psalms 51:4, because it was against God's command written in men's minds, though not yet published by express word or writing; and against God's honour; and that here in a particular manner, because it would have rendered Isaac's original, and thereby God's promise, doubtful.