Bukhari

Narrated Um Khalid bint Khalid: I heard the Prophet seeking refuge with Allah from the punishment of the grave.

Narrated Mus`ab: Sa`d used to recommend five (statements) and mentioned that the Prophet I used to recommend it. (It was) "O Allah! I seek refuge with You from miserliness; and seek refuge with You from cowardice; and seek refuge with You from being sent back to geriatric old age; and I seek refuge with You from the affliction of this world (i.e., the affliction of Ad-Dajjal etc.); and seek refuge with You from the punishment of the grave."

Narrated `Aisha: Two old ladies from among the Jewish ladies entered upon me and said' "The dead are punished in their graves," but I thought they were telling a lie and did not believe them in the beginning. When they went away and the Prophet entered upon me, I said, "O Allah's Apostle! Two old ladies.." and told him the whole story. He said, "They told the truth; the dead are really punished, to the extent that all the animals hear (the sound resulting from) their punishment." Since then I always saw him seeking refuge with Allah from the punishment of the grave in his prayers.