NET

21 This took place to fulfill the Lord’s message spoken through Jeremiah and lasted until the land experienced its sabbatical years. All the time of its desolation the land rested in order to fulfill the seventy years.

Darby

21 to fulfil the word of Jehovah by the mouth of Jeremiah, until the land had enjoyed its sabbaths. All the days of its desolation it kept sabbath, to fulfil seventy years.

KJV

21 To fulfil the word of the LORD by the mouth of Jeremiah, until the land had enjoyed her sabbaths: [for] as long as she lay desolate she kept sabbath, to fulfil threescore and ten years.

Strong's

21 To fulfil^H4390 the word^H1697 of the LORD^H3068 by the mouth^H6310 of Jeremiah^H3414, until the land^H776 had enjoyed^H7521 her sabbaths^H7676: for as long as^H3117 she lay desolate^H8074 she kept sabbath^H7673, to fulfil^H4390 threescore and ten^H7657 years^H8141.