خِيفَ is the passive perfect. Passive vocalisation changes the beginning to kasrah, and weak-letter development yields a medial ī sound. The active خَافَ (“he feared”) is therefore contrasted with the passive خِيفَ (“he/it was feared”).
Word / formMeaning / explanation
خَافَthird-person masculine singular, active.
خِيفَthird-person masculine singular, passive.
خِفْتُactive first person; خُفْتُ — passive first person, distinguished by the first vowel.
Voice cannot always be inferred from a single initial vowel without the rest of the form and its context.