David was critically ill (Psalm 30:2); he almost died. The Lord made him ill because David was proud and thought that he would never be moved. Then the Lord hid his face (Psalm 30:6–7). That means there was an absence of divine favour. David prays but receives no answer. He feels alone. God is gone. That leads to David’s mourning. When and why do you mourn? You mourn when a loved one has left you. In Israel, the people clothed themselves with a sackcloth as a sign of mourning. A sackcloth was also used to express penitence. David repented that he was proud and had forgotten the Lord.
11 You have turned for me my mourning into dancing; you have loosed my sackcloth and clothed me with gladness,