The Tafseer of Imaam As-Sa'dee regarding Allaah's statement (which means): Do they wait until the angels come to them...

Allaah The Most High says:  Do they wait until the Angels come to them, or that your Lord should come, or that some of the signs of your Lord should come. That day, in which some of the signs of your Lord will come, no good will it do a person to believe then, if he wasn't one who believed before, or gained good with their belief Say: "Wait, we too are waiting." [An'aam:158] 

Imaam As-Sa'dee (rahimahullaah) said:

He The Most High says: Do they wait, those who are continuant in their oppression and stubbornness 'until the Angels come to them' with the forefront to punishment and The Last Day, that the Angels may come to them to seize their souls. For indeed if they reach such a situation, their belief will not benefit, nor righteous actions, 'or that your Lord should come' to judge between his servants and to reward the good-doers and the evil doers, 'or that some of the signs of your lord should come' pointing to the closeness of the hour. 'That day, in which some of the signs of your Lord will come' that go beyond what is ordinary, that by way of it (these signs) you come to know that the hour has drawn close, and that the Qiyaamah (the last day) has drawn closer. 

No good will it do a person to believe then, if he wasn't one who believed before, or gained good with their belief.   

Meaning: if some of the signs of Allah come into existence, Eemaan will not benefit the disbeliever (at this point), nor the believer that has shortcomings, that he may increase in good actions thereafter, but that which will benefit is the Eemaan that was with the person before, and that which they had from good (actions) before some of the signs of their lord comes. 

And the wisdom in this is apparent, for indeed the Eemaan that is of benefit is the Eemaan of the unseen (Qhayb), and was by the worshippers' free-will. As for if the signs come into existence, and the affair is one of witness, then no benefit will remain in Eemaan (in believing at this point), because it then resembles Eemaan (belief) due to necessity, like the Eemaan of the one who is drowning or is under ablaze and the likes, from those that if they saw death they would abstain from that which they where upon, like He the Most High said:

So when they saw Our punishment, they said: "We believe in Allaah Alone and reject (all) that we used to associate with Him as partners. Then their Faith (in Islamic Monotheism) could not avail them when they saw Our punishment. (Like) this has been the way of All?h in dealing with His slaves. [Ghafir 40:84-85]   

And many authentic narrations have come from the Prophet, that what is intended by 'some of the signs of Allah,' the rising of the sun from the west, and that when the people see this they will all believe, but their belief will not be of benefit to them, and at this point the door of Tawbah (repentance) will be closed.   

And in this verse is proof for the position of Ahlus-Sunnah wal Jamaa'ah affirming 'Actions of Free Will and Choice,' like Istiwaa (ascension) and Nuzuul (descension) and Ityaan (coming) to Allaah the Blessed the Most High, without Tashbeeh (resemblance) to him with the characteristics of the creation. And this is common in the Book and the Sunnah.   

And in it (this verse), the rising of the sun from the west is from the signs of the hour, and that Allah the Most High is Hakeem, and his common tradition, that the type Eemaan that is of benefit is the one that is chosen (by the servant) due to his own free will and not by compulsion, like has preceded.   

And that mankind should obtain good with their Eemaan, for indeed obedience and righteousness and piety only benefits and increases if the servant possesses Eemaan. But if the heart is empty of Eemaan, none of these things will be of benefit to him.

Source: Tayseerul Kareem Ar-Rahmaan, page 158