Jamieson, Fausset and Brown on Jeremiah 31:20

20. Is Ephraim my dear son? &c.--The question implies that a negative answer was to be expected. Who would have thought that one so undutiful to His heavenly Father as Ephraim had been should still be regarded by God as a "pleasant child?" Certainly he was not so in respect to his sin. But by virtue of God's "everlasting love" (Jr 31:3) on Ephraim's being "turned" to God, he was immediately welcomed as God's "dear son." This verse sets forth God's readiness to welcome the penitent (Jr 31:18, 19), anticipating his return with prevenient grace and love. Compare Lu 15:20: "When he was yet a great way off, his father saw him and had compassion," &c.

spake against--threatened him for his idolatry.

remember--with favor and concern, as in Ge 8:1; 30:22.

bowels ... troubled for him--(De 32:36; Is 63:15; Ho 11:8)--namely, with the yearnings of compassionate love. The "bowels" include the region of the heart, the seat of the affections.