«إِذَا قَطَعَتْ وَصَلَتْ»
When it cuts, it also joins.
Cutting and joining are opposed actions, apparently contradictory when asserted of one object. Once the needle is identified, the tension resolves: piercing enables thread to unite fabric.
The paradox functions as a riddle. It delays recognition while quietly supplying the clue, rewarding the reader who can connect the figurative description to the concrete implement.