Albert Barnes Commentary John 5:38

"And ye have not his word abiding in you: for whom he sent, him ye believe not." — John 5:38 (ASV)

His word abiding in you. His law does not abide in you—that is, you do not regard or obey it. This was the third thing that he charged them with.

1. They had not obeyed the command of God.
2. They had not regarded his manifestations, either in the times of the old dispensation, or now through the Messiah.
3. They did not yield to what he had said in the revelation of the Old Testament.

For whom he has sent. God had foretold that the Messiah would come. He had now given evidence that Jesus was he; but now they rejected him, and this was proof that they did not regard the word of God.