In his commentary on Psa 90-150, Allen P. Ross noted the following about the text of Psa 110:3:
The Masoretic text has
a difficulty with the spelling of the second word: “dawn” has a letter mem prefixed to it. MT has מֵרֶחֶם מִשְׁחָר. If the
second word had the מ repointed
it would be another preposition: “from the womb, from the dawn”; if the letter
were deleted, the words would read “from the womb of the dawn” (most English
Bibles do this). Support comes from the spelling of “womb,” which indicates a
construct (“womb of”). Either a letter was accidently added to the second word
(dittography), or we have a variant spelling of the noun. The Greek has “out of
the womb before the dawn” or “morning star,” ἐκ γαστρὸς
πρὸ ἑωσφόρου, suggesting it read the preposition on the second
word. The editors of BHS suggest the מ on the second word came by dittography and should be deleted. (Allen P. Ross, A Commentary on the Psalms, 3 vols. [Kregel Exegetical Library; Grand
Rapids, Mich.: Kregel Academic, 2016])
