Untimely cheerfulness is unbearable. When you have a heavy heart, you are in no mood to sing or have someone to sing to you. To take away someone’s coat when it is cold, would be a cruel thing to do.
To pour vinegar upon nitre (Baking soda), is to cause it to hiss and lose its component power. Vinegar stings when applied wrongly.
When our brothers and sisters are sad, it is cruel to rejoice in their sorrow.
Under Gods command 