God Comforts Those Steadfast in Faith
Jeremiah 31:16 (ESV) … “Thus says the Lord: ‘Keep your voice from weeping, and your eyes from tears, for there is a reward for your work, declares the Lord, and they shall come back from the land of the enemy.’”
This text on sorrow in Jeremiah is connected to the great sorrow experienced in Bethlehem when Herod killed all those children in his effort to kill Christ (Matthew 2:16–18). What the verse is telling us, is that our broken hearts over the sinfulness and sorrow of this world will one day have consolation we find in Christ. On that day in Bethlehem God fulfilled his long-awaited promise.
P.G. Ryken puts it this way, “this is the dark side of Christmas, the raw wound of the Nativity. Army boots tromped and stamped across the manger scene. Though Christ was born and rescued, the babes of Bethlehem were slaughtered and buried.”[1]
While the prophet Jeremiah did not have all the answers to the problem of suffering in our world, he did know where to turn for comfort. Our source of comfort in this world is to look to Christ in faith. To rejoice that by the grace of God, his prophecy did not end in tears but laughter. To rejoice that by the grace of God, those tears and our tears find a greater joy in the kept covenant promise of God.

Much of this world will never make a lot of sense to us, but we tread on in faith. Trusting in the ever powerful and providential hand of God.
[1] Ryken, P. G. (2001). Jeremiah and Lamentations: from sorrow to hope (pp. 452–453). Wheaton, IL: Crossway Books.