Tafsir of Al-Isra 17:68

{أفأمنتم} The hamza is for denunciation (inkār), and the fa is a conjunction connecting to an omitted clause, the estimation of which is: "Have you been saved, so you felt secure [thereby], and that led you to turn away?"

{أن يخسف بكم جانب البر} If you ask: "What is the grammatical object of yakhsifu (to cause to sink)?" I say: jānib al-barr (the side of the land) is the direct object, just as al-arḍ (the earth) is in His saying: "So We caused the earth to swallow him and his house" (Al-Qasas: 81). And bikum (with you) is a circumstantial qualifier (ḥāl). The meaning is: that He causes the side of the land to sink—meaning He overturns it—while you are upon it.

If you ask: "What is the meaning of mentioning 'the side'?" I say: It means that all sides and directions are equal in His power. He has, in every side—whether land or sea—a prepared cause of destruction. The side of the sea is not uniquely designated for this; rather, if drowning is in the side of the sea, then in the side of the land there is its equivalent, which is the khasf (sinking). For it is a concealment beneath the soil, just as drowning is a concealment beneath the water. Land and sea are equal to Him; He is capable of [inflicting] in the land just as He is capable of [inflicting] in the sea. Therefore, a rational person should have an equal fear of God in all sides and wherever he may be.

{أو يرسل عليكم حاصبا} It is the wind that taḥṣubu—meaning it throws ḥaṣbā’ (pebbles). It means: If He does not strike you with destruction from beneath you by sinking, He will strike you with it from above you by a wind He sends upon you, containing pebbles with which He pelts you, making it more severe for you than drowning in the sea.

{وكيلا} [Meaning] someone who would take charge of averting that from you.

{أم أمنتم} That He strengthens your motives and provides for your needs until you return and board the sea from which He saved you, and [yet] you turned away; so He takes vengeance upon you by sending {عليكم قاصفا}—which is the wind that has a qaṣīf, meaning a loud, intense sound, as if it is tataqaṣṣaf (breaking/cracking). It is also said: It is the wind that passes by nothing except that it shatters it.

{فيغرقكم} It is read with the tā’ (referring to the wind) and with the nūn (referring to Us). Likewise, nakhsifu (We cause to sink), nursilu (We send), and nu‘īdukum (We return you) are read with both the yā’ and the nūn.

{تبيعا} The tabī‘ is the claimant (muṭālib), from His saying: "And payment [to the victim's family] with good conduct" (Al-Baqarah: 178), meaning a demand. Al-Shammākh said: As the debtor takes refuge from the claimant (tabī‘). It is said: "So-and-so is a tabī‘ to so-and-so for his right," meaning he is in control over him, demanding his right from him. The meaning is: We do what We do to them, and then you will find no one to demand from Us [an account of] what We have done, by way of seeking victory over Us or seeking revenge on our part. This is similar to His saying: "And He fears not the consequence thereof" (Ash-Shams: 15).

{بما كفرتم} By your ingratitude for the blessing. He means: their turning away when He saved them.