“Like one who takes away a garment in cold weather and like vinegar on soda is one who sings songs to a heavy heart” (Proverbs 25:20).
As Solomon wrote in more detail in Ecclesiastes 3:1-8, there is a time for everything under the sun. To try to rejoice with those who mourn is grievously unwise, because it is unnatural. As Solomon illustrates it in this proverb, such foolishness borders on cruelty—like taking a warm and needed garment away from someone in cold weather. It produces a vigorous and unnecessary reaction—like putting vinegar on soda. Some things just do not mix.
Weep with those who weep. Rejoice with those who rejoice (Rom. 12:15). Do not be so socially obtuse that you think a joyful song is appropriate for those with a heavy heart. If someone is hurting, keep your words few and your eyes wide open.
It is a very simple rule of thumb: If you or loved ones are suffering, pray; when everyone is cheerful, sing psalms (James 5:13).
