Tafsir of Luqman 31:16

"O my son, indeed it..."

It has been recited as mithqala habbatin (in the accusative case) and mithqalu habbatin (in the nominative case).

As for the one who recites it in the accusative: The pronoun refers to the matter of the deed, whether it be an evil act or a good one. That is: even if it were, in its smallness and insignificance, like a mustard seed, and even if it were—despite its smallness—in the most hidden and secure place, such as the hollow of a rock, or anywhere else in the upper or lower worlds, "Allah will bring it forth" on the Day of Resurrection and hold its doer accountable for it. "Indeed, Allah is Subtle"—His knowledge reaches every hidden thing—"Acquainted"—knowing its essence. Qatadah said: "Subtle in extracting it, Acquainted with its resting place."

As for the one who recites it in the nominative: The pronoun refers to the "story" or "matter." The word mithqal (weight) is treated as feminine because it is annexed to habbah (seed), as in the poet's saying: As the shaft of the spear became saturated with blood.

It is narrated that Luqman’s son asked him: "Do you see that if a seed were in the depths of the sea—that is, in its diving grounds—Allah would know it?" He replied: "Indeed, Allah knows the smallest of things in the most hidden of places; for a seed in a rock is more hidden than one in the water."

It is said: The "rock" is the one beneath the earth, which is Sijjin, where the deeds of the disbelievers are recorded.

It has also been recited as fatakun (with a kasra under the kaf), derived from the verb wakana al-ta'iru yakinu, meaning when a bird settles in its waknah (nest), which is its place of rest at night.

"O my son, establish prayer, enjoin what is right, forbid what is wrong, and be patient over what befalls you. Indeed, that is of the matters [requiring] determination."