How did Muhammad bin Salman broach the topic of his appointment as Crown Prince with his dad?

There must be an awkward conversation which took place between Muhammad bin Salman and his father.  I mean, there certainly was a moment in which Bin Salman went to his father and said: look dad. You don't look good and you are not getting any younger.  I have a hunch you are leaving us soon.  I see that you issue the royal decrees at once.  I don't want you to die before attending to this matter otherwise it will all be over for me.