Catena Aurea on John 5:19–20: John Chrysostom

Or thus; That the Son can do nothing of Himself, must be understood to mean, that He can do nothing contrary to, or displeasing to, the Father. And therefore He does not say that He does nothing contrary, but that He can do nothing; in order to shew His perfect likeness, and absolute equality to the Father. Nor is this a sign of weakness in the Son, but rather of goodness. For as when we say that it is impossible for God to sin, we do not charge Him with weakness, but bear witness to a certain ineffable goodness; so when the Son says, I can do nothing of myself, it only means, that He can do nothing contrary to the Father.