John Gill Commentary Genesis 22:24

"And his concubine, whose name was Reumah, she also bare Tebah, and Gaham, and Tahash, and Maacah." — Genesis 22:24 (ASV)

And his concubine, whose name [was] Reumah
Not an harlot, but a secondary wife, who was under the proper and lawful wife, and a sort of a head servant in the family, and chiefly kept for the procreation of children; which was not thought either unlawful or dishonourable in those times such as was Hagar in Abraham's family: she bore also Tebah, and Gaham, and Thahash, and Maachah ,
of whom we have no account elsewhere; only it may be observed, that here Maachah is the name of a man, which sometimes is given to a woman, (1 Kings 15:13) .