"Say: He is Allah, the One, Allah the eternally besought." [Sûrah al-Ikhlâs: 1-2]
The Qur'ân is miraculous in its eloquence. There is meaning in every choice of word and every stylistic decision. One of these decisions that may seem minor to us, is in fact rich in nuance. This is the decision in the Qur'ân whether to use a pronoun or to repeat the noun.

This is a stylistic device which is frequently found in the Qur'ân. We see it where Allah commands us in the Qur'ân: "Say: He is Allah, the One, Allah the eternally besought." [Sûrah al-Ikhlâs: 1-2]

We see in this verse that the name "Allah" is repeated twice in succession. A pronoun was not used instead. The verse does not read: "He is Allah the One, He is the eternally besought…"

There are blessings, of course, in the repetition of Allah's name. However, this repletion here clearly adds to the richness of the verse's meaning and to its power. The oneness of Allah is brought into sharper focus. Through repeating Allah's name, the verse emphasizes that Allah being besought by all is itself an emphasis of his being the one and only God, the creator and sustainer of everything and everyone in Creation.

`Abd al-Qâhir al-Jurjânî, the great scholar of Arabic literary style, writes in his seminal work Dalâ'il al-I`jâz (Evidences of the Qur'ân's Miraculousness):
"Say: He is Allah, the One, Allah the eternally besought." has a delightful, stately, and noble quality of speech that is not lost upon a discerning reader. Had the pronoun "He" been employed instead of the explicit repetition of Allah's name – had the verse read "Say: He is Allah, the One, He is the eternally besought." – then you would not feel the same effect.

The same can be said for the verse: "So he began searching their sacks before his brother's sack, then brought it out from his brother's sack."
Indeed, al-Jurjânî points us to another good example of this stylistic device, where Allah says: "So he began searching their sacks before his brother's sack, then brought it out from his brother's sack." [Sûrah Yûsuf: 76]

We see in this verse that Allah repeats the word "brother", saying "brother's sack" twice in close succession instead of saying "his sack" the second time, which is the more usual way of speaking.

In this case, the repetition of the word "brother" is used to impart a greater sense of disclosure and discovery to a critical and dramatic moment in Yûsuf's story. Yûsuf has the stolen object pulled out of his brother's sack last after the other sacks are searched. The identification with Joseph's brother is a major thing, since it is evidence incriminating his brother of theft. This is used by Yûsuf as a means of keeping his brother with him.

Another example of this stylistic device is seen in the verse: "We sent down the (Qur'an) in truth, and in Truth has it descended: and We sent you only to give glad tidings and to warn. " [Sûrah al-Isrâ': 105]

Allah could have said: "We sent down the Qur'ân in truth, and thus it has descended". However, we can clearly see how effective the repletion of the word "truth" is here. It emphasizes the purity and clear certainty of the Qur'ân's message by reiterating mention of its truth from the angle of Allah sending it down and from the angle of it being a revealed book.

Another example is seen in the verse: "Allah promises the hypocrites, men and women, and the disbelievers the hellfire for their abode. It will suffice them. Allah curses them, and theirs is lasting torment. " [Sûrah al-Tawbah: 68]

In his landmark commentary of the Qur'ân, al-Alûsî offers the following comment on this verse:
[The verse] says: "…Allah curses them". There is an explicit reiteration of Allah's name here, in spite of its already being stated in the phrase "Allah promises the hypocrites…" The end of the verse could have read: "He curses them, and theirs is a lasting torment." However, by explicitly mentioning the name "Allah" again, it gives a forceful impression of the severity of Allah's anger at the hypocrites.
These are but a few examples. There are numerous others. We should read the Qur'ân attentively and consider the other places where Allah the Qur'ân chooses to repeat a noun instead of relying on a pronoun. In this way, we will have a greater appreciation of the Qur'ân's richness and beauty.

And Allah knows best.