If thou knewest. She did not ask for grace and for pardon. Oh, this woman was so ignorant. Not only did she not know the Person sitting there was the only Saviour, but she was also ignorant of the way of salvation. If thou knewest the gift of God.
Salvation is a free gift.
She did not know that. She had been brought up under a system of legalism. This becomes clear from what she says in vv. They do not see that true religion is a matter of the heart, not outward observances. Legalism is in our blood.