Tafsir of Al-Hujurat 49:17

(They consider it a favor to you that they have accepted Islam): That is, they count their Islam as a favor upon you. A favor (minnah) is a grace for which the bestower seeks no reward from the one upon whom it is bestowed. It is derived from al-mann (the cut), because the intent behind it is the satisfaction of a need. Al-Raghib said: It is a burdensome grace, derived from al-mann (the weight) used for measuring; its burdensomeness lies in its magnitude or the hardship in bearing it.

(That they have accepted Islam): This is in the position of an object for "they consider a favor," due to the implication of the meaning of "counting/reckoning." Or, it is an instance of the ellipsis of a preposition, such that the verbal noun is in the accusative case due to the removal of the preposition or genitive by the implied preposition—meaning: they consider it a favor to you by their Islam. The same can be said regarding His saying, exalted is He: (Say: Do not consider your Islam a favor to me). It either means "do not count your Islam as a favor upon me," or "do not consider yourselves as doing me a favor by your Islam." Abu Hayyan permitted that (that they have accepted Islam) be an object for the sake of which the action is performed (maf'ul li-ajlihi), meaning: they act as though they are doing you a favor for the sake of their Islam.

(Rather, Allah confers a favor upon you in that He has guided you to the faith): That is, not as you claimed in your saying "we have believed." This does not contradict His saying, exalted is He: (Say: You have not yet believed), or [it means] guidance as a generic indication, so their belief does not necessarily follow, thus avoiding contradiction with the previous negation of faith.

Abdullah and Zayd ibn Ali read it as (idh hadakum) using idh for causation. It was also read as (in hadakum) using the conditional in.

(If you are truthful): That is, in the claim of having faith. It is linked to the truthfulness, not to the guidance, so do not be negligent. The apodosis of the condition is omitted, indicated by what precedes it, meaning: "then to Allah belongs the favor upon you."

The subtlety and grace within the context of the verse should not be overlooked: that which emanated from those Bedouins, Allah, exalted is He, termed "Islam"—exposing the falsehood of their claim "we have believed," i.e., "we have brought about faith"—in the context of them expressing a favor. The Glorified One negated that it was belief as they claimed. When they considered their actions a favor to the Messenger, may Allah bless him and grant him peace, the Glorified said to His Messenger, peace be upon him: "They consider it a favor to you, which is not worthy of being considered a favor, from their speech which is rightfully termed 'Islam'." So say to them: "Do not consider your Islam as a favor to me," meaning: your speech, which is named Islam in My sight, not faith. Then the Exalted said: "Rather, Allah counts a favor upon you in that He aided you with His facilitation, in that He guided you to the faith that you claimed."

In His saying, exalted is He, (your Islam), by way of annexation (genitive construction), there is evidence that it is not something to be considered, and that it is something befitting their likes; so how could it be worthy of being a favor? To alert that the faith which is to be considered is that which He, the Almighty and Majestic, did not annex [to them]. He, the Glorified, alerted by His saying, the Almighty and Majestic: (If you are truthful), that this is a lie from them. The subtlety lies in the presentation of the refutation, then the response regarding the favor, while observing the nuances in each, and the perfection of beauty is in the epilogue with His saying, exalted is He...