Commentaries:
Jesus would have had to have been with the Father to see the Father do these things. He even asserts Himself as having the powers that go with the Godhead: to raise the dead.
In verses 22-23, Christ is clearly asserting and affirming to those people that He is one of the Godhead. One is called the Father. The other is called the Son. The plural Elohim is simple to understand within this instance.
John W. Ritenbaugh
The Nature of God: Elohim
Other Forerunner Commentary entries containing John 5:21:
Ephesians 6:4