Thomas Aquinas Commentary Jeremiah 31:7-9

"For thus saith Jehovah, Sing with gladness for Jacob, and shout for the chief of the nations: publish ye, praise ye, and say, O Jehovah, save thy people, the remnant of Israel. Behold, I will bring them from the north country, and gather them from the uttermost parts of the earth, [and] with them the blind and the lame, the woman with child and her that travaileth with child together: a great company shall they return hither. They shall come with weeping; and with supplications will I lead them: I will cause them to walk by rivers of waters, in a straight way wherein they shall not stumble; for I am a father to Israel, and Ephraim is my first-born." — Jeremiah 31:7-9 (ASV)

Here, the prophet discusses the order of operation, and concerning this, there are three points.

1. He urges them to exultation with the words exult in joy. The psalmist expresses a similar sentiment: Exult in God our help, sing to the God of Jacob (Psalms 80:2).

   To express this exultation, he suggests taunting the enemy: and neigh, as an insult, against the head of the nations—that is, against the king of Babylonia or of the Assyrians, who held you captive. As Habakkuk says, Shall they not rise up suddenly that bite you, and those that tear you be stirred up, and you shall be prey for them? (Habakkuk 2:7). He also calls for divine praise: make a sound, with psalteries and instruments of this kind.

2. He gives the order of the redemption, beginning with the words, behold, I shall lead them. He describes the starting point of their return: from the land of the north. He also describes the company of those returning with the phrase among whom, as if to say, “Indeed, no one will be hindered from returning by any bodily infirmity.” As Isaiah says, Then shall the lame man leap as a deer (Isaiah 35:6).

   He then describes the manner of their return. It will be with weeping—some weeping for joy at their return, and others weeping when they saw the devastation of the land. As it is written in Ezra, So that one could not distinguish the voice of the shout of joy, from the noise of the weeping of the people (Ezra 3:13). God says, And I shall bring them back in mercy, delivering them from their shame of mind. Isaiah also says, I shall gather you with great mercies (Isaiah 54:7).

   They will return through the torrents of water, meaning they will travel easily by sailing down them, with good roads alongside them. This description removes the sense of hardship and weariness from the journey. As Proverbs says, You shall walk confidently in your way, and your foot shall not stumble (Proverbs 3:23).

3. He gives the reason for this redemption, which stems from God’s fatherly affection for His people: for I have become a father. Because He is a father, He cannot help but have mercy on them. Among all the peoples, Israel was the firstborn (Exodus 4:22).

   Now, the birthright was given to the sons of Joseph, as it says in 1 Chronicles 5. Within Joseph's family, Ephraim was set before Manasseh (Genesis 48:13–19). For this reason, the status of firstborn is here given to Ephraim.