Tafsir of Ghafir 40:78

{And among them are those [about] whom We have not related to you} It is said: God sent eight thousand prophets: four thousand from the Children of Israel, and four thousand from the rest of mankind. It is narrated from Ali (may God be pleased with him) that God Almighty sent a black prophet, and he is among those whom He did not relate to him.

This is in response to their demanding signs from the Messenger of God (peace be upon him) out of stubbornness. It means: We have sent many messengers, and it was not for any one of them to {bring} [a sign]. So, who am I to bring a sign from what you demand, except if God wills and permits its arrival?

{Then, when the command of God comes} A threat and a warning following their demand for signs. The "command of God" is the Resurrection.

{The falsifiers} They are the stubborn ones who demanded signs, yet when the signs came to them, they denied them and labeled them sorcery.

{It is God who made for you the grazing livestock that you may ride from them, and from them you eat. And for you in them are [other] benefits, and that you may attain upon them a need in your breasts; and upon them and upon ships you are carried. And He shows you His signs. So which of the signs of God do you deny?}