Antiquities of the Jews 1.344 (Whiston I.21.3) — William Whiston (1737), public domain (Perseus digital edition, CC BY-SA 3.0 for the digitisation) (public domain)
And when he was gone thence, and was come over against Ephrata, he there buried Rachel, who died in child-bed: she was the only one of Jacob's kindred that had not the honor of burial at Hebron. And when he had mourned for her a great while, he called the son that was born of her Benjamin, because of the sorrow the mother had with him. These are all the children of Jacob, twelve males and one female.
Reproduced in full. Translation: William Whiston (1737), public domain (Perseus digital edition, CC BY-SA 3.0 for the digitisation) (Public domain).
Why Pitre cites it
Rachel died 'in childbirth' and her son was called Benjamin 'because of the suffering which he had caused his mother' — the first-century memory of Rachel as a mother of sorrow.
Notes
Whiston reads 'because of the sorrow the mother had with him' (key phrase given as 'because of the sorrow/suffering he had caused his mother' — same sense). Perseus places the Loeb marker [343] at the head of this paragraph; the naming of Benjamin falls in 1.344. Whiston's footnote on Benoni/Benjamin omitted. The Perseus URL with ':section=344' returned 'No document found'; the Whiston chapter/section form above works.