Tafsir of Al-Insan 76:5

{Indeed, the righteous} is a commencement in explaining the excellent state of the grateful ones, following the explanation of the evil state of the disbelievers. They are mentioned under the title of "the righteous" (al-abrar) to indicate what they have earned of noble honor, while simultaneously providing a fresh description of praise for them.

Al-abrar is the plural of barr, like rabb and arbab (lords), or bar (righteous) like shahid and ash-had (witnesses), based on the rule that fa’il may be pluralized as af’al. The barr is the obedient one who is expansive in doing good. It is also said that it refers to one who fulfills the right of Allah Almighty and fulfills vows. According to al-Hasan, it is he who does not harm even an ant and does not consent to evil.

{They will drink} in the Hereafter from a ka’s (cup). The ka’s is, as al-Zujaj said, the vessel when it contains drink; if it is empty, it is not called a ka’s. Al-Raghib said that the ka’s is the vessel together with the drink inside it, and each of the two is called a ka’s individually. The common view is that it applies in reality to a glass vessel when it contains wine, and metaphorically to the container [otherwise]. What is intended here, it is said, is the wine; thus, "min" (from) is for partiality (tab’idiyyah) or for explanation (bayaniyyah). It is also said it refers to the glass containing the wine, in which case "min" is for the beginning of the action (ibtida’iyyah). His saying, "Its mixture is camphor," is more clearly suited to the first view.

It is apparent that this is in the vein of [the phrase], "And Allah is ever All-Knowing, All-Wise," and the use of the verb [in the past tense] is for confirmation and perpetuity. It is said that [the verb kana] is complete, as in His saying, "Be, and it is."

The mizaj (mixture) is that which is mixed with something, like the hizam (girth) is that which one is bound with; it is a noun for the instrument. Kafur (camphor), according to al-Kalbi, is a spring in Paradise whose water is in the whiteness of camphor, its coolness, and its fragrance. It is declined [with a nunation] to conform with the [ending of the] verses. The discourse implies the omission of a genitive, meaning: "water of camphor." The sentence is an attribute of the cup. This statement [regarding the spring] contradicts the apparent meaning, and perhaps if no report is sound regarding it, it is not accepted. ‘Abdullah recited qafuran with a qaf instead of a kaf, and the two often alternate in words, as they say ‘arab yuqah and wakah.