2 Samuel 12:16

12:16 Then David prayed to God for the child and fasted. He would even go and spend the night lying on the ground.

2 Samuel 12:22-23

12:22 He replied, “While the child was still alive, I fasted and wept because I thought, ‘Perhaps the Lord will show pity and the child will live. 12:23 But now he is dead. Why should I fast? Am I able to bring him back? I will go to him, but he cannot return to me!’”