CHRYSOSTOM:
The Sadducees know of nothing incorporeal, perhaps not even God, so thick-headed are they. Consequently, they are also unwilling to believe that there is a resurrection.
Why didn’t [Jesus] appear to him before he fell into danger? Because, as always, it is in afflictions that God consoles. For then he appears more desirable, as he trains us even in the midst of dangers.
HILARY OF POITIERS:
[This passage] shows that since human beings cannot, so to speak, be fused back into God or themselves coalesce into one undistinguished mass, this oneness must arise from unity of will, as all perform actions pleasing to God and unite with one another in the harmonious agreement of their thoughts. Therefore, it is not nature that makes them one but will.