C. F. Keil and Franz Delitzsch on 2 Samuel 14:27

2Sa 14:27

Unto Absalom there were born three sons, and one daughter named Tamar, who was beautiful in figure. Contrary to general usage, the names of the sons are not given, in all probability for no other reason than because they died in infancy. Consequently, as Absalom had no sons, he afterwards erected a pillar to preserve his name (2Sa 18:18). The daughter’s name is probably given as a proof of Absalom’s great affection for his sister Tamar, whom Amnon had violated.The lxx have this additional clause, καὶ γίνεται γυνὴ Ῥοβαὰμ υἱῷ Σαλωμὼν καὶ τίκτει αὐτῷ τὸν Ἀβιά (and she became the wife of Rehoboam the son of Solomon, and bore him a son named Abia). Although this is quite at variance with 1Ki 15:2, where it is stated that the wife of Rehoboam and mother of Abia (Abijam) was named Maacah, the clause had been adopted by Thenius, who regards it as original, though for reasons which Böttcher has shown to be worthless.