Heaviness in the heart of a man maketh it stoop - Sorrow of heart, hopeless love, or a sense of God's displeasure - these prostrate the man, and he becomes a child before them.

But a good word maketh it glad - A single good or favorable word will remove despondency; and that word, "Son, be of good cheer, thy sins are forgiven thee," will instantly remove despair.

heaviness

Proverbs 14:10 The heart knows his own bitterness; and a stranger does not intermeddle with his joy.

Proverbs 15:13,15,23 A merry heart makes a cheerful countenance: but by sorrow of the heart the spirit is broken...

Proverbs 17:22 A merry heart does good like a medicine: but a broken spirit dries the bones.

Proverbs 18:14 The spirit of a man will sustain his infirmity; but a wounded spirit who can bear?

Nehemiah 2:1,2 And it came to pass in the month Nisan, in the twentieth year of Artaxerxes the king, that wine was before him: and I took up the wine...

Psalm 38:6 I am troubled; I am bowed down greatly; I go mourning all the day long.

Psalm 42:11 Why are you cast down, O my soul? and why are you disquieted within me? hope you in God: for I shall yet praise him...

Mark 14:33,34 And he takes with him Peter and James and John, and began to be sore amazed, and to be very heavy...

but

Proverbs 12:18 There is that speaks like the piercings of a sword: but the tongue of the wise is health.

Proverbs 15:23 A man has joy by the answer of his mouth: and a word spoken in due season, how good is it!

Proverbs 16:24 Pleasant words are as an honeycomb, sweet to the soul, and health to the bones.

Proverbs 25:11 A word fitly spoken is like apples of gold in pictures of silver.

Proverbs 27:9 Ointment and perfume rejoice the heart: so does the sweetness of a man's friend by hearty counsel.

Isaiah 50:4 The Lord GOD has given me the tongue of the learned, that I should know how to speak a word in season to him that is weary...

Zechariah 1:13 And the LORD answered the angel that talked with me with good words and comfortable words.

2 Corinthians 2:4-7 For out of much affliction and anguish of heart I wrote to you with many tears; not that you should be grieved...

Of Having Confidence in God when Evil Words are Cast at Us
"My Son, stand fast and believe in Me. For what are words but words? They fly through the air, but they bruise no stone. If thou are guilty, think how thou wouldst gladly amend thyself; if thou knowest nothing against thyself, consider that thou wilt gladly bear this for God's sake. It is little enough that thou sometimes hast to bear hard words, for thou art not yet able to bear hard blows. And wherefore do such trivial matters go to thine heart, except that thou art yet carnal, and regardest …
Thomas A Kempis—Imitation of Christ