Plain Understanding
Asking protection from those who practice sorcery and dark arts, specifically referencing the ancient occult practice of tying knots in a string and blowing malicious incantations into them to inflict hidden harm.
Historical Context (Al-Qurtubi)
In the incident with Labid ibn al-A'sam, his daughters assisted him by tying eleven knots in a cord, blowing dark incantations onto each. As the Prophet ﷺ recited the eleven combined verses of the Mu'awwidhatayn (5 in Al-Falaq, 6 in An-Nas), a knot miraculously untied with each verse, lifting the heavy psychological and physical burden from him entirely.