Tafsir of An-Nahl 16:18

(And if you should count the favor of Allah, you cannot enumerate it)

This is a comprehensive reminder of the favors of Allah, the Exalted, following the enumeration of a group of them, and separating the two by His saying, the Exalted: "Is then He who creates like him who does not create?" This was stated to hasten the compelling of the proof and to silence the opposition immediately following the detailed explanation of the deeds that are proofs of monotheism. Even though these [deeds] were not intended specifically from the aspect of creation—since their indication of Him is necessarily apparent from the aspect of bestowing blessings as well—because they were among the consequences of the former aspect, there was no need to explicitly state them.

Then, He explained their state by way of summation: that is, if you were to count the favors of Allah, the Exalted, which have overflowed upon you—from what has been mentioned and what is yet to be mentioned—you would not be able to encompass or determine their number, let alone fulfill the gratitude due for them. A discussion on the verification of this has preceded, in accordance with that which Allah, the Exalted, has granted.

(Indeed, Allah is Forgiving)

In that He conceals the ingratitude that has preceded from you and the failure to fulfill their [the favors'] rights, and He does not hasten your punishment for that.

(Merciful)

In that He bestows them upon you, despite your deserving of cessation and deprivation because of what you commit and what you leave of the various types of disbelief and disobedience, among which is equating the Creator with others. Each of these two—the concealment and the bestowal—is a favor, and what a favor it is. Thus, the sentence serves as a justification for the ruling of inability to enumerate. The mention of "Forgiving" precedes "Merciful" because the removal of an impediment (takhliyah) takes precedence over the adornment with something positive (tahliyah).