Genesis 40:23 - The Sin of Forgetting

Yet did not the chief butler remember Joseph, but forgat him.

This was a case of "out of sight, out of mind" in the face of good times. The butler had good intentions on helping Joseph but he forgot him as though he were dead (Psalm 31:12). When times are good we have a bad habit of forgetting those that helped us succeed (Amos 6:6, Hosea 13:6). This sin of forgetfulness happens when we become overly preoccupied with our own affairs which overshadows the interest of others.