John 16:21

When a woman is in labor, she is in pain, for her time has come, but when the baby is born, she forgets her pain because of her joy that a human being has been born into the world.

Revelation 7:14-17

I answered him, "You know, my lord." He said to me: "These are the people who are coming through the great persecution, who have washed their robes and made them white in the blood of the Lamb.

Treasury of Scripture Knowledge

Summary

Because thou shalt forget thy misery, and remember it as waters that pass away:

Bible References

Because

John 16:21
When a woman is in labor, she is in pain, for her time has come, but when the baby is born, she forgets her pain because of her joy that a human being has been born into the world.
Revelation 7:14
I answered him, "You know, my lord." He said to me: "These are the people who are coming through the great persecution, who have washed their robes and made them white in the blood of the Lamb.