Tafsir of Al-Feel 105:2

(Did He not make their plot go astray) – this is a summary statement of what Allah Almighty did to them. The interrogative particle (hamzah) is for the purpose of affirmation, as previously mentioned. For this reason, what follows it is conjoined to the interrogative sentence, as if it were said: "He has indeed made their plot to dismantle the Kaaba, destroy it, and divert the honor of its people, a matter of waste and nullification, by destroying them in the most hideous manner."

The root of tadlil (going astray) is taken from the expression "it went astray from him" (dalla 'anhu) when something is lost. Thus, it is used metaphorically here to mean nullification. From this, Imru' al-Qais was called al-Dalil (the one who went astray) because he lost and wasted his father’s kingdom.