al-Nisāʾ 4:174-175

Yā ayyuha'l-nāsu qad jāʾakum burhānun min rabbikum wa anzalnā ilaykum nūran mubīnā · Fa-amma'lladhīna āmanū bi'llāhi wa'ʿtaṣamū bihī fa-sa-yudkhiluhum fī raḥmatin minhu wa faḍlin wa yahdīhim ilayhi ṣirāṭan mustaqīmā

"O mankind! A burhān has come to you from your Lord, and We have sent down to you a clear light. As for those who believe in God and hold fast to Him, He will admit them into a mercy from Himself and a bounty, and will guide them to Himself by a straight path."

ب-ر-ه-ن — it is counted a four-letter root; the lexicographers also debate its relation to ب-ر-ه and do not agree on any settled derivation. Nothing definite is said in this commentary about the origin of the word.

On its meaning, however, they agree: a decisive and binding proof.

The word occurs at al-Qaṣaṣ 28/75 as well (hātū burhānakum), and there it is used as a demand.

The same word, once a demand and once a response. I record this as an observation about word order.

The root ع-ص-م had occurred in this sūra at the hundred and forty-sixth verse too (wa'ʿtaṣamū bi'llāh) and was treated there. I rely on that treatment.

The same verb, in two separate places in the sūra, and in both a holding fast.