Passage
At the same time, saith the LORD, will I be the God of all the families of Israel, and they shall be my people.
At the same time, saith the LORD, will I be the God of all the families of Israel, and they shall be my people.
Jeremiah 31:1 At the same time, saith the LORD, will I be the God of all the families of Israel, and they shall be my people.
Jeremiah 31:2 Thus saith the LORD, The people which were left of the sword found grace in the wilderness; even Israel, when I went to cause him to rest.
Jeremiah 31:3 The LORD hath appeared of old unto me, saying, Yea, I have loved thee with an everlasting love: therefore with lovingkindness have I drawn thee.
The verse centers on "same", "time", "saith", "lord", "families", "israel", "shall", and "people". It is saying that the verse draws attention to "same" and "time", so its meaning should be read from those terms before moving to application.
The next verse adds "Thus saith the LORD The people which...", so "same" and "time" should be read forward into that movement. In Jeremiah context, the local focus is covenant, worship, and faithfulness.
A plain takeaway is to answer the verse's own emphasis on "same" and "time" with trust shaped by these words, not by a vague optimism outside the passage.