Allah (swt) is The Giver and The Merciful Creator.
Everything between the seven skies and the folds of the Earth are subjected to the mercy of Allah (swt). Note, when Allah (swt) talks about the Resurrection Day He (swt) uses the attribute of Merciful and not any other of His Names such as The Mighty or The Avenger, that is to reassure his slaves about His mercy.
During that time, no human being will be able to say anything, as the affairs have ended and the world of responsibilities has come to a stop. So no speech whatsoever.