Tafsir of Luqman 31:13

(And when Luqman said to his son)—his name is Taran, according to what Al-Tabari and Al-Qutaybi have said. It is also said: Mathan, with a tha (ث); and it is said: An'um; and it is said: Ashkam—the latter two being on the measure of af'al; and it is said: Mashkam, with a mim replacing the hamza.

The word (and when / idh) is governed by a suppressed verb, "remember." It is also said that it may be an adverbial time for "We gave" [i.e., wa-ataynahu al-hikmata idh qala—"And We gave him wisdom when he said"], with the preceding clause being abbreviated due to the indication provided by what follows.

His saying, the Exalted: (while he was exhorting him)—a circumstantial sentence. Exhortation (wa'z), as Al-Raghib stated, is a reprimand conjoined with intimidation. Al-Khalil said: It is reminding [someone] of good in a way that softens the heart.

(O my son)—a diminutive [form] of compassion and love, not a diminutive of belittlement. As someone said: “But when a thing is loved, the letters of the diminutive become enamored of it out of the intensity of longing.” And another said: “I did not utter 'my little beloved' out of belittlement, but rather the name of the thing is sweetened by the diminutive.”

Al-Bazzi read [the word] here (O my son / ya bunayya) with the stillness [of the ya]; and in the later instance (O my son, indeed it / ya bunayya innaha) with the kasrah on the ya; and in (O my son, establish / ya bunayya aqim) with its fat-hah. It is said there is stillness in the first and the third, and kasrah in the middle. Hafs and Al-Mufaddal, from Asim, read with the fat-hah in all three, based on the assumption of ya bunayya [originally bunayya'a], where the fat-hah suffices for the alif. The remaining seven [reciters] read with the kasrah in all of them.

(Do not associate partners with Allah)—It is said his son was a disbeliever, and for that reason, he forbade him from polytheism and continued to exhort him until he embraced Islam; the same is said regarding his wife.

Ibn Abi al-Dunya extracted in Na't al-Kha'ifin, from Al-Fadl al-Raqashi, who said: Luqman did not cease exhorting his son until he died.

And he extracted from Hafs ibn Umar al-Kindi who said: Luqman placed a pouch of mustard seeds and began to exhort his son with a sermon, taking out a mustard seed [each time]. When the mustard seeds ran out, he said: "O my son, I have exhorted you with a sermon that, had it been preached to a mountain, it would have cracked." And his son cracked [and died].

It is also said he was [already] a Muslim, and the prohibition of polytheism was a warning to him against it occurring from him in the future. The apparent [meaning] is that the ba in bi-Allah is related to the verb [prohibit]. Whoever stops at (Do not associate) makes the ba one of oath—that is, "I swear by Allah."

(Indeed, polytheism is a great injustice)—The apparent [meaning] is that this is part of Luqman’s speech, and the words of Muslim in his Sahih necessitate this. The statement is an explanation for the prohibition or the cessation of polytheism. It is said: It is a speech from Allah, the Exalted, disconnected from the speech of Luqman, yet connected to it in confirming the meaning. Polytheism is an "injustice" because it involves placing a thing in other than its rightful place, and it is "great" because it involves equating the One from whom there is no blessing except from Him, with one who possesses no blessing.