One of the most quoted and loved passages of the Bible has an unexpected textual history.
At Matt 21:16 Jesus is made to say:
Have you never read, ‘FROM THE MOUTHS OF INFANTS AND NURSING BABIES YOU HAVE PREPARED PRAISE FOR YOURSELF’?”
Many recognize that the Psalm 8:2,3 here quoted in part is a form of the passage found in the LXX. The MT reads differently:
Out of the mouth of babes and sucklings You have established strength because of Your adversaries, in order to put an end to enemy and avenger.
Many, many commentators and theologians has commented on this passage since antiquity, in part because the texts reads awkwardly and defies an easy explanation.
What do sucklings have to do with Yahweh's defeat of his enemy?
Firstly we must appreciate this is likely the reason the LXX translators opted to creatively alter the text. But it gets complicated.
Psalm 8:2b-3:New Proposals for Old Problems
MARK S. SMITH
Psalm 8 is one of the psalms that have attracted the greatest attention from biblical scholars. While the picture of humanity and the cosmos in Psalm 8 and the psalm's relations with the priestly story of creation in Gen 1 : 1- 2:4a have been the objects of frequent study, the textual difficulties involved in Ps 8:2b-3 have been addressed less often. Despite the variety of proposals for understanding these verses, no rendering advanced to date has been judged satisfactory. The reason lies largely with the text itself, which hardly conforms to the general canons of syntax and parallelism for biblical poetry.
Smith continues by reviewing the suggestions and the links to a creation myth wherein Yahweh defeats his primeval enemies in the habituating the earth for humans.
Verse 3 evokes a cosmic conflict at the time of the creation of the universe. The two expressions for cosmic enemies, côlelîm wěyoněqím and *Dôyêb ûmitnaqqëm, are semantically (though not syntactically) parallel. This proposal is informed by the frequent comparison of this passage with CTA 23,offered first by C. Shedl in 1964.11 Called "suckers" ( ynqm ) as in Ps 8:3, the cosmic foes, known also to be children of the god El, devour all the beasts of the cosmos and are remanded to the desert for seven || eight years until they are allowed into the sown region. The putative parallels with Ps 8:3 involve (1) divine "suckers," (2) their appetite that threatens all animals (stressed in Ps 8:3 with the image of their mouth), and (3) the possible cosmogonie setting of this myth. Evidently Ps 8:3 alludes to a related myth (though it is hardly necessary that the same myth be involved). On this view, cólělím wěyoněqím and Doyēb ûmitnaqqêm may be regarded as examples of hendiadys, rendered as such in the translation above. Accordingly, the prepositional phrase preceding cólělím wěyoněqím, namely, mippî (literally, "from the mouth of") does not refer to the material from which the stronghold is built; instead, it constitutes the threat for which the stronghold is need.
In short the proposal is that the passage has been corrupted and originally was a hymn to Yahweh as mighty defeater of his enemies, who include "suckers", supernatural beings who were children of El but presented a threat to life. A number of other researchers have connected these elements as the referenced provided in his article show.
The proposed alternate translation is:
Let me sing/ celebrate your splendor over the heavens.
From the mouth of (sucker children) suckling babes you established a strong place,
For your stronghold you indeed ended the avenging enemy.
By way of parallel another difficult passage in Proverbs 30:15 has defied simple explanation.
To the leech (Aluka, sucker) are two daughters, 'Give, give'. Lo, three things are not satisfied, Four have not said 'Sufficiency;'
Many commentators have suggested we have a conflation of proverbs with the verse 15a reference to the sucker having insatiable daughters having lost it's conclusion and 15b simply being the intro to what is now in verse 16.
The ‛Alûka hath two daughters: Give! Give! (lost )
Three are never satisfied; Four say not: Enough! The under-world and the closing of the womb, The earth is not satisfied with water, and the fire saith not: Enough!
This enigmatic sucker has been linked to the Arabic cognate 'awleq' which refers to a sucking demon. (e.g. De Moor).
So....what we have is another plausible ancient reference to a sucking demon related to the Arabic and Ugarit mythology.
It is perhaps informative that that was a widely held understanding among Rabbinic and later Jewish mythologists. They expanding this sucking demon into elaborate tales of a shapeshifting bloodsucking witch/demon name Alukah. Alukah - Wikipedia
Naturally most modern commentators argue against this conclusion, however their suggestions are IMO inadequate.