The gory details:
	All of the notes of Fmi7 (F, Ab, C, Eb) are part of the scale which sounds best with Db MA7, the Db MA7 scale (Db, Eb, F, Gb, Ab, Bb, and C).
	Because Fmi7 is the chord that is built on the third scale step of Db Major, music theorists label Fmi7 as a iii mi7 in Db Major.
	The first three tones of Fmi7 (root, minor 3rd and perfect 5th) serve as the major 3rd, perfect 5th, and major 7th of the DbMA7. The 4th note of Fm7, Eb, would add a 9th to a DbMA7. To put a different way, you can build a DbMA9 chord by adding a Db root below a Fmi7.
	A DbMA9 just sounds like a DbMA7 with a little color added.