2 Samuel 12:22

And he said, while the child was yet alive
And so there was hope it might be continued:

I fasted and wept;
or sought the Lord by prayer, and fasting, and weeping, that the threatening might not take place, that the child's life might be spared:

for I said;
within himself, thus he reasoned in his own mind:

who can tell [whether] God will be gracious to me, that the child may
live?
and in hope of this he kept praying, fasting, and weeping; he could not tell but God might repent of the evil he had threatened, as in some cases he has done; see ( Joel 2:13 Joel 2:14 ) ( Jonah 3:9 Jonah 3:10 ) . Abarbinel thinks that David fasted and wept to hide this matter from his wife, and his servants, and did not let them know that this was in his punishment, that the child should die.