How Did the Angels Know?

When Allah (swt) told the angels that I will place the khalīfah on earth, what did they say? They said: qālū a-tajʿalu fīhā man yufsidu fīhā wa yasfiku al-dimāʾ, wa naḥnu nusabbiḥu bi-ḥamdika wa nuqaddisu lak. Will You place therein those who will make mischief therein and shed blood, while we glorify You with praises and thanks? Are You going to place on earth someone who will shed blood and cause corruption, when we are glorifying You?

How did the angels know that human beings will corrupt on the face of the earth? Ādam was not placed on the world yet. Why did the angels say: You are going to place someone who will cause corruption and shed blood in the world? There are two explanations given.

One explanation is that Allah (swt) told the angels ahead of time that this is what human beings will do. The second explanation — and this is mentioned by Ibn ʿAbbās — is that jinn were living in this world before, and they caused corruption, and they shed blood, and they fought with each other, and they corrupted this world, and they caused so much evil. And then Allah (swt) sent on them armies from the angels, and also Iblīs, to fight against them. And then they were pushed and cornered to the islands of the ocean. So the angels said: why are You going to place someone on earth who would cause corruption and shed blood again?

So these are the two explanations given. There is no hadith to support any one of them; these are two explanations given to the ayah. Allah (swt) said: qāla innī aʿlamu mā lā taʿlamūn — I know what you know not. I know what you know not.