Torah Temimah cites Bava Kamma 67b.
“That which he stole” — teaches that on his own robbery he adds a fifth, but he does not add a fifth on his father’s robbery.
Miyut of personal robbery — fifth only on one’s own act.
Heirs restore the principal of the father’s theft but do not add the chomesh of this verse. The fifth is tied to the personal act of robbery, not to the mere possession of stolen goods.