Leviticus 26:41

And [that] I also have walked contrary unto them
Showed no regard unto them, as if he took no care of them, or in a providential way concerned himself for them, but let what would befall them; yea, came out in the way of his judgments against them, as if he was an enemy to them, (See Gill on Leviticus 26:24);

and have brought them into the land of their enemies;
should acknowledge the hand of God in it, that he himself brought them out of their own country into an enemy's land, as Assyria, Babylon, and other nations: and that this was not the chance of war, or owing to the superior power or skill of their enemies, but to the just judgment of God upon them for their sins, who on that account delivered them up into the hands of their enemies:

if then their uncircumcised heart be humbled;
their foolish proud heart, as the Targums of Onkelos and Jonathan; it signifies a sinful, wicked, hard, and impenitent heart, brought to a sense of sin, to repentance and humiliation for it. Jarchi interprets it, "or if their uncircumcised heart" as in ( Exodus 2:23 ) ; and observes another sense of the word, "perhaps their uncircumcised heart" not only would in words confess their sins, but be truly humbled at heart for them:

and they then accept of the punishment of their iniquity;
take it well at the hand of God, bear it patiently without murmuring, or thinking themselves hardly dealt by, but freely owning it is less than their iniquities deserve; or complete and finish the punishment of their sins, as Aben Ezra, which upon their humiliation should be put an end to, and cease. Jarchi takes the word in the sense of atonement and pacification, as if by their chastisement their sins were expiated ^F4, and God was pacified toward them: but rather it denotes the free and full pardon of their sins, manifested to them upon their repentance and humiliation for sin.