The Fates are one incarnation of the Triple Goddess (like the Norns) -- the precursor to the Faerie Queens.
One version (from the Perseus legends, if I recall correctly) has them as three hags sharing a magical eye that they pass around between them.
Most particularly, when Harry "summons" Mother Winter, in Cold Days, two of the names he uses for her are Athropos (which I assume is an alternate spelling for Atropos, the eldest of the Fates and the one who cuts the threads of life) and Skuld (one of the Norns).
So... I'd guess that Rashid is saying he got the Eye from the Mothers when they assigned him his role as Gatekeeper.