Tafsir of Yunus 10:19-20

{And mankind was not but one community} They were monotheists (hunafa’), united upon a single religion without differing among themselves. This was during the era of Adam until Cain killed Abel. It is also said: this refers to the time after the Flood, when God did not leave a single home of the disbelievers upon the earth.

{And had it not been for a word that preceded from your Lord} Namely, the deferment of judgment between them until the Day of Resurrection.

{it would have been judged between them} Immediately regarding that in which they differed, and the one in the right would have been distinguished from the one in the wrong. His word preceded with deferment due to a wisdom that necessitated this world be a place of obligation (taklif), and that world be a place of reward and punishment.

{And they say, "Why is a sign not sent down to him from his Lord?"} They desired a sign from among those they proposed, while they did not count the great, numerous signs that had been sent down to him—signs the likes of which were not sent down to any other prophet. The Qur’an alone suffices as a sign that remains for the duration of time; it is unique and strange among miracles, and subtle in its path. They treated its revelation as if it were no revelation at all, as if no sign had ever been sent down, to the point that they said, "Why is a sign not sent down to him from his Lord?" This was due to the excess of their stubbornness, their persistence in rebellion, and their immersion in error.

{Say, "The unseen belongs only to God"} Meaning: He is the One exclusively possessing the knowledge of the unseen, keeping it to Himself. Neither I nor anyone else has knowledge of it. This means that the reason for withholding the requested signs is a matter of the unseen that no one knows except Him.

{So wait} For the descent of what you have proposed.

{I am with you among those who wait} For what God will do to you because of your stubbornness and your denial of the signs.

{And when We give the people a taste of mercy after adversity which has touched them, at once they have a plot against Our signs. Say, "God is swifter in plotting. Indeed, Our messengers record that which you plot."}