Charles Spurgeon Commentary John 20:9

"For as yet they knew not the scripture, that he must rise from the dead." — John 20:9 (ASV)

They did not understand it; even John himself did not until then.

The rest of the disciples had never placed that interpretation on our Lord's words which was their clear and simple meaning, namely, that he would rise from the dead. I would not be surprised if there are other words of Scripture, with regard to the future, that we would understand if we took them exactly as they stand in the Word; but we have assigned other meanings to them, and consequently do not see further into them.