Tafsir of Al-Anbiya' 21:57

Meaning: I will strive diligently to break them. The essence of al-kayd (plotting) is the use of stratagem to bring about harm while manifesting the contrary; it necessitates exertion, and thus, it is used here to denote that. It signals the difficulty of seizing the opportunity and that it is dependent upon employing artifice so that they might be cautious in guarding them, thereby making the triumph over the objective more complete in its rebuke. This was, on his part (peace be upon him), a resolve to guide them toward the realization of their misguidance through another method. This is not contradicted by what has been narrated from Qatadah, who said: "We believe he (peace be upon him) said this where they could not hear him." It has been said that one man among them heard it, and others say a group of their weaker ones, those who were walking at the end of the procession on the day they went out to the festival. The idols were seventy, and it is also said seventy-two.

Mu'adh ibn Jabal and Ahmad ibn Hanbal read it as Billahi (بِاللهِ) with the Ba—the second letter of the alphabet—which is the fundamental letter of oath-taking, as it enters upon both manifest nouns and pronouns, and the verb of the oath is explicitly stated or omitted with it. The Ta is a substitute for the Waw, as in tujah (تجاه). The Waw stands in the place of the Ba due to the affinity between them, given that both are labial consonants, and because the Waw conveys a meaning close to that of attachment, as mentioned by many grammarians. However, this was critiqued in al-Bahr on the grounds that there is no evidence for this, and al-Suhayli refuted it. What inquiry demands is that none of these letters is an origin for the other. Some differentiate between the Ba and the Ta by noting that the Ta carries an additional nuance of astonishment (ta'ajjub). The astonishment here concerns his (peace be upon him) embarking upon an affair involving such risk. The consensus of grammarians is that it is permissible for the Ta to carry the sense of astonishment, and it is permissible for it not to, while it is the Lam (in the oath) that requires the sense of astonishment. Others differentiate between them in usage, noting that the Ta is not used except with the Majestic Name of Allah or with "Lord" (Rabb) when annexed to the Ka'bah, albeit rarely.

"After you have turned your backs..."

Meaning: From their worship toward your festival. Isa ibn Umar read it as tawallaw (تولوا), derived from al-tawalli (turning away), by omitting one of the two Tas—the second according to the Basrans, and the first according to Hisham. This reading is supported by the words of the Exalted: "So they turned away from him, retreating."