What?
The tossing of the saber in the first scene is not refusing to fight his father - he just did and won - do you even Star Wars? It's refusing to take his fathers place, embracing the dark side, fulfilling a dark side destiny, becoming more man than machine - the emperor even says so - and Luke thinking, listening, adding it all up, looking at his machine hand and....rejecting this. Rejecting to become a Darth. Rejecting to kill his father. Rejecting to adhere to the Emperor and becoming his lackey instead of Darth Vader. NEVER! I'll never turn to the dark side. You've failed your highness. I'm a Jedi. Like My father before me. Thus rejecting the dark side of the force - naive, but strong in faith.
But sure. Other than it's the same character tossing the same (?) lightsaber with the same hand and again rejecting the force, all the bs that goes with it - training, failing, padawans, dark side following light side, being dragged in again regardless of seeking exile, force severance - reaching this conclusion, being wiser, crankier, and a poor script - and both films sucking from there on out - no connection