to whom He grants permission.” (1)
Then He said: “until, when the dread is lifted from their hearts, they will say, ‘What has your Lord said?’” (2)

The pronoun in the phrase “from their hearts” refers to those implied in the words “to whom He grants permission,” for the angels are included among those to whom He gives leave. This is also indicated by His saying: “Say: Call upon those whom you claim besides Allah; they possess no power….” (3) The angels come under this address, so He stripped them of ownership, partnership, aid, and intercession—except by His permission. He went on to clarify the matter even further: when He speaks, they cannot remain firm before His speech, nor can they stay composed; rather, they are seized with fear. Then, when (4) the terror is removed from them, they say, “What did your Lord say?” They answer, “The truth.” (5)

What follows ḥattā here is therefore a complete clause. In His words, “when the dread is lifted from their hearts, they will say, ‘What has your Lord said?’,” the verb that governs idhā is their saying, “What….” Idhā is an adverb referring to the future and carries an implicit conditional meaning—i.e., when the dread departs from their hearts, they say, “What has your Lord said?” The endpoint after ḥattā may be a single word, as mentioned earlier, or an entire clause, as in His saying:

“And whoever turns away from the remembrance of the All-Merciful, We assign to him a devil who becomes his companion; (36) they certainly bar them from the path while they think they are rightly guided, (37) until, when he comes to Us, he will say, ‘Oh, would that there were between me and you the distance of the two Easts!’” (6)

And His saying:

“It is He who conveys you by land and sea, until, when you are on board the ship and they sail with them before a pleasant wind and they rejoice in it, there comes upon it a violent wind, and the waves come upon them from every direction, and they think they are beset.” (7)