Because

Genesis 41:51
Joseph named the firstborn Manasseh, saying, "God has made me forget all my hardship and all my father's household."

Proverbs 31:7
Let him drink and forget his poverty, and remember his misery no more.

Ecclesiastes 5:20
For a man seldom considers the days of his life, because God keeps him occupied with the joy of his heart.

Isaiah 54:4
Do not be afraid, for you will not be put to shame; do not be humiliated, for you will not be disgraced. For you will forget the shame of your youth, and remember no more the reproach of your widowhood.

Isaiah 65:16
Whoever invokes a blessing in the land will do so by the God of truth, and whoever takes an oath in the land will swear by the God of truth. For the former troubles will be forgotten and hidden from My sight.

John 16:21
A woman has pain in childbirth because her time has come; but when she brings forth her child, she forgets her anguish because of her joy that a child has been born into the world.

Revelation 7:14-17
"Sir, " I answered, "you know." So he replied, "These are the ones who have come out of the great tribulation; they have washed their robes and made them white in the blood of the Lamb. . . .

as waters

Job 6:15
But my brothers are as faithless as a wadi, as seasonal streams that overflow,

Genesis 9:11
And I establish My covenant with you: Never again will all life be cut off by the waters of a flood; never again will there be a flood to destroy the earth."

Isaiah 12:1, 2
In that day you will say: "O LORD, I will praise you. Although You were angry with me, Your anger has turned away, and You have comforted me. . . .

Isaiah 54:9
"For to Me this is like the days of Noah, when I swore that the waters of Noah would never again cover the earth. So I have sworn that I will not be angry with you or rebuke you.