fayth (Middle English) comes from Old French fei, from Latin fides, from Latin fido, from Proto-Italic feiðō, from Proto-Indo-European bʰéydʰeti, from Proto-Indo-European bʰeydʰ- — to compel, force; to trust.
Ancestry of “fayth”, step by step
fayth traces back through 3 separate lines of ancestry.