John Gill Commentary Genesis 39:8

"But he refused, and said unto his master`s wife, Behold, my master knoweth not what is with me in the house, and he hath put all that he hath into my hand:" — Genesis 39:8 (ASV)

But he refused, and said unto his master's wife
Reasoning with her about the evil nature of the crime she tempted him to, which to commit would be ingratitude, as well as injury to his master, and a sin against God; by which it appears that Joseph was a partaker of the grace of God, and that this was in strong exercise at this time, by which he was preserved from the temptation he was beset with: behold, my master does not know what is with me in the house ;
what goods or money are in it: and he has committed all that he has into my hand :
such confidence did he repose in him, therefore to do such an injury to him as to commit adultery with his wife, would be making a sad return, and acting a most ungrateful part for such favour shown him.