Why did Allah send Iblis to Paradise to tempt Adam, and did Allah warn Adam about Iblis before he entered Paradise? And why did Allah respond to Iblis’s request to be granted respite until the Day of Resurrection, instead of destroying him?

God has guided us not to trouble ourselves with such questions, and we must submit and surrender. God is not questioned about what He does, but they will be questioned. God created Iblis and tested His servants with him for profound wisdom. God had warned Adam against Iblis before his entry into Paradise, as Allah Almighty said: "So We said, 'O Adam, indeed this is an enemy to you and to your wife. So let him not expel you both from Paradise, lest you suffer'" and "And their Lord called to them, 'Did I not forbid you from that tree and tell you that Satan is to you a clear enemy?'" God did not answer Iblis's prayer to be granted respite until the Day of Resurrection; rather, He delayed him until the Day of the Appointed Time (the first blowing of the trumpet), and this is an increase in his affliction and misery.