The first occurrence.
Though He slay me, yet will I trust in Him, but I will maintain my own ways before Him. Job 13:15
The primitive root.
Strong’s H6991 קטל qatal, a primitive root meaning, “to slay,” only used poetically. The 3-letter root is quph + tet + lamed.
quph ק = on the horizon, thus condense, circle, time
tet ט = basket, thus surround, contain, hold, mud
lamed ל = shepherd’s staff, thus teach, yoke, to, bind
The story: To be condensed (quph, as light is condensed to the sun when it is on the horizon, becoming smaller than it was, on the verge of disappearing altogether) so as to be contained (tet), that is, to be cut short, cut down, directed by authority (lamed).