Most readers will know that, until August 1951, the Roman Gospel for the Assumption was S Luke 10: 38-42 (Jesus, Martha, and Mary). The passage originally had Luke 11: 27-28 tacked on at the end; and this combination of pericopes is still used in the Byzantine and Mozarabic Rites as the Gospel for this day (and, indeed, for other Marian festivals).
I suspect an Eastern origin.
I have always taken this to be a reference to Mary as the True Hesychast; the one who Listens quietly to Christ; the perfect Daughter of Israel who Hears YHWH. She is the Mistress and Owner of Mount Athos, the exponent of Hesychia. If one goes through S Luke's Chapters 10-11 looking out for the connections established by the verb akouein (hear) in its enhanced sense of listen obediently, this composite Gospel reads distinctly well.
Gueranger quotes S Bruno of Asti as interpreting thus: Mary, like Martha, 'received' Jesus, and not only into her home but into her womb; and Mary, like Mary, listened silently and pondered.
What I would be interested to know is comments on these passages by Fathers of East or West ... comments which relate either or both parts of the pericope to the Mystery of the Dormition/Assumption, or to her ministry of Intercession.