Abdullah ibn Umar reported that Allah's Messenger (pbuh) mentioned the two angels of the grave so Umar asked "Is our reason preseved with us then oh Messenger of God? He (pbuh) replied "Yes, as is your present state" then Umar said "In that case I would throw a stone into the angel's mouth! meaning (my answer will be so convincing the angel will be dumfounded]" [Targhib wal Tarhib]

The Prophet said: "There dominate ninety-nine serpents over the unbeliever in the grave. They constantly bite him and sting him till there comes the Hour of Resurrection. These serpents are so poisonous that if one of them exhales in the earth, no vegetation would ever grow upon it." [Mishkat]