user29976: I was reading the question Has there been any blunders in resignation? and it occurred to me that a particularly good sportsman might refuse to accept an opponent's resignation if they knew the opponent was not in a hopeless position.
Some quick Googling suggests that the rules (or at least some sets of rules) do allow you to refuse a resignation from your opponent, so it is possible that this has happened in a high level match. I would be interested to know if it has ever happened. The conditions would be the same as the previous question i.e. a GM or near GM level match and excluding resignations for reasons not related to the state of the game.

user15223: Similar things have happened, but it's not because one player misevaluated the position.
Source

Having beaten down the desperate resistance of the opponent, [GM David Navara] achieved the position where either mate or the loss of the rook was inevitable and at that moment he offered a draw. The situation was clarified by both Grandmasters.
David Navara: – On the 35th move I accidentally touched both pieces, the King and the Bishop. I wanted to move my bishop on d6, but clipped the King also, however, Moiseenko claims that I have first touched the King, but I am not sure about that. Any move with the King would lead to the loss of the piece, however, Moiseenko did not insist that I make a move according to the touch rule. I did not want to be referred to as an unethical chess player who managed to win in an unfair way, that is why at the end, having achieved the winning position, I offered a draw.
Alexander Moiseenko: – Navara on the 35th move first touched the King. I told him: the King moves. However, I realized that my opponent accidentally made this mistake, it is not possible that he could so easily blunder the piece. This is the reason I did not insist on his move with the King.

Final position:
2K5/8/2k5/8/8/q7/8/3R4 b - - 0 1

Black wins after 115. Kb8 Qb3+ forking the rook (115. Kd8 Qf8#). Notably Moiseenko didn't actually resign, but he was obviously about to, since it was mate in a few more moves.

user4418: 
Some quick Googling suggests that the rules (or at least some sets of rules) do allow you to refuse a resignation from your opponent

This does not reflect the FIDE Laws of Chess. According to Article 5.1.2:

5.1.2 The game is won by the player whose opponent declares he resigns. This immediately ends the game.

This means that no player, GM or otherwise, is permitted to refuse an opponent's resignation in a FIDE rated event.
Of course in a friendly or skittles match such things are allowed and may have occurred but not in a "serious" FIDE rated game.

29976: <p>I was reading the question <a href="https://chess.stackexchange.com/questions/37122/has-there-been-any-blunders-in-resignation">Has there been any blunders in resignation?</a> and it occurred to me that a particularly good sportsman might refuse to accept an opponent's resignation if they knew the opponent was not in a hopeless position.</p>
<p>Some quick Googling suggests that the rules (or at least some sets of rules) do allow you to refuse a resignation from your opponent, so it is possible that this has happened in a high level match. I would be interested to know if it has ever happened. The conditions would be the same as the previous question i.e. a GM or near GM level match and excluding resignations for reasons not related to the state of the game.</p>
 15223: <p>Similar things have happened, but it's not because one player misevaluated the position.</p>
<p><a href="https://www.chessdom.com/moiseenko-and-navara-remind-the-world-about-the-fair-play/" rel="nofollow noreferrer">Source</a></p>
<blockquote>
<p>Having beaten down the desperate resistance of the opponent, [GM David Navara] achieved the position where either mate or the loss of the rook was inevitable and at that moment he offered a draw. The situation was clarified by both Grandmasters.</p>
<p>David Navara: – On the 35th move I accidentally touched both pieces, the King and the Bishop. I wanted to move my bishop on d6, but clipped the King also, however, Moiseenko claims that I have first touched the King, but I am not sure about that. Any move with the King would lead to the loss of the piece, however, Moiseenko did not insist that I make a move according to the touch rule. I did not want to be referred to as an unethical chess player who managed to win in an unfair way, that is why at the end, having achieved the winning position, I offered a draw.</p>
<p>Alexander Moiseenko: – Navara on the 35th move first touched the King. I told him: the King moves. However, I realized that my opponent accidentally made this mistake, it is not possible that he could so easily blunder the piece. This is the reason I did not insist on his move with the King.</p>
</blockquote>
<p>Final position:</p>
<pre><code>2K5/8/2k5/8/8/q7/8/3R4 b - - 0 1
</code></pre>
<p>Black wins after 115. Kb8 Qb3+ forking the rook (115. Kd8 Qf8#). Notably Moiseenko didn't actually resign, but he was obviously about to, since it was mate in a few more moves.</p>
 4418: <blockquote>
<p>Some quick Googling suggests that the rules (or at least some sets of rules) do allow you to refuse a resignation from your opponent</p>
</blockquote>
<p>This does not reflect the <a href="https://handbook.fide.com/chapter/E012018" rel="noreferrer">FIDE Laws of Chess</a>. According to Article 5.1.2:</p>
<blockquote>
<p>5.1.2 The game is won by the player whose opponent declares he resigns. <strong>This immediately ends the game</strong>.</p>
</blockquote>
<p>This means that no player, GM or otherwise, is <em>permitted</em> to refuse an opponent's resignation in a FIDE rated event.</p>
<p>Of course in a friendly or skittles match such things are allowed and may have occurred but not in a &quot;serious&quot; FIDE rated game.</p>
