John Calvin on Genesis 40:14-15

14. Show kindness I pray thee unto me Fac quaeso mecum misericordiam. Although the expression show kindness is used among the Hebrews to describe the common exercise of humanity; there is yet no doubt that Joseph spoke simply as his own sad and afflicted condition suggested, for the purpose of inclining the mind of the butler to procure him help. He insists, however, chiefly on this, that he had been thrust into prison for no crime, in order that the butler might not refuse his assistance to an innocent man. For although they who are most wicked find patrons; yet commendation elicited by importunity, which rescues a wicked man from deserved punishment, is in itself an odious and infamous thing. It is, however, probable that Joseph explained his whole cause, so that he fully convinced the butler of his innocence.