John 16:21

When a woman may bring forth she has sorrow, because her hour has come: but when the little child may be born, she remembers her suffering no more, for the joy that a man has been born into the world.

Revelation 7:14-17

And I said unto him, My lord, thou knowest. And he said to me; These are those coming up out of great tribulation, 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 may bring forth she has sorrow, because her hour has come: but when the little child may be born, she remembers her suffering no more, for the joy that a man has been born into the world.
Revelation 7:14
And I said unto him, My lord, thou knowest. And he said to me; These are those coming up out of great tribulation, who have washed their robes, and made them white in the blood of the Lamb.