Gregory the Dialogist

That the disciples were slow in believing our Lord's resurrection was not so much a weakness of theirs as it is our strength. For the resurrection itself through their doubts was manifested by many proofs; and whilst we read and acknowledge them, what do we but become firmer through their doubting?

Catena Aurea by Aquinas ↗

Bede

And they, hearing that he was alive, and had been seen by her, did not believe. Because the disciples were slow to believe in the Lord's resurrection, it was not so much their infirmity as our (so to speak) future firmness. For that very resurrection was shown to them, who doubted, through many proofs, which we, recognizing while reading, are otherwise solidified by their doubt. For Mary Magdalene, who believed sooner, rendered me less a service than Thomas, who doubted longer. …

On the Gospel of Mark ↗