David was in mourning (Ps 35:11-35:14)

“Malicious witnesses rise up.

They ask me about things

That I do not know.

They repay me evil for good.

My soul is forlorn.

But as for me,

When they were sick

I wore sackcloth.

I afflicted myself with fasting.

I prayed with head bowed on my bosom.

I grieved as like for a friend or a brother.

I went about

As one who laments a mother.

I was bowed down.

I was in mourning.”

This seems to be something more family orientated. There were malicious witnesses against David who turned his good deeds into evil. He was forlorn and wore sackcloth in mourning for their illness. He fasted and bowed his head in prayer. He grieved as if it was his friend, his brother, or his mother. Somehow someone did not appreciate all his care and mourning.