The first argument of Jesus in defence of himself is: “My Father is working still, and I am working” (Jn 5: 17). Jesus claims authority over Sabbath and hence, the right to work on the Sabbath. Jesus states that God, his Father is working on the Sabbath day. So when he too is doing the same thing, Jesus is claiming to have divine authority. In fact, Jews believed that God had the prerogative of doing three things even on the Sabbath day: to give life (birth), to take away life (death), to give rain (source of prosperity and life). Jesus uses this view as an argument to defend himself because in healing the man on the Sabbath day Jesus was giving life. So he was merely using the prerogative natural to him as God himself.
Through this teaching Jesus explains the meaning of the healing he performed at Bethesda. That the “Son of Man” has authority over the Sabbath is a teaching found in the Synoptic tradition in the context of the Sabbath controversies (cf. Mk 2: 13-36; Mt 12: 2-14; Lk 6: 1-11). In the Synoptic Gospels Jesus defends himself, first from the human point of view and second, on the basis of Scripture reminding them of what David had done entering the house of God and what he did was otherwise prohibited. But here in the Gospel of John, Jesus’ claim is regarding the prerogative of God.
The Jews accuse Jesus of two things: he made himself equal to God; violating Sabbath; and he addressed God “my Father” (Abba). God is transcendent and nobody is equal to him. He cannot be addressed by any human being as “my Father”, an address used in the family expressing familiarity and intimacy. It would be a sign of lack of respect if this were to be used for God.