Can a bad end befall a person who has worshipped Allah his whole life? And is the Prophet's (peace and blessings of Allah be upon him) saying, "Indeed, one of you does the deeds of the people of Paradise until there is nothing between him and it except a cubit, then the Book overtakes him, and he does the deeds of the people of Hellfire and enters it. And indeed, one of you does the deeds of the people of Hellfire until there is nothing between him and it except a cubit, then the Book overtakes him, and he does the deeds of the people of Paradise and enters it," general without conditions or signs indicating one's destiny? And what are the deeds that lead to a good end?

The meaning you mentioned is established in several hadiths, among them that a man may perform the deeds of the people of Paradise while he is from the people of Hell, and he may perform the deeds of the people of Hell while he is from the people of Paradise. Know that the outcome is the inheritance of what preceded it. A bad ending does not befall someone whose inner self is upright and whose outward actions are righteous; rather, it befalls someone whose inner disposition contains corruption or doubt. Thus, whoever worships Allah for a long time and whose inner self is righteous is usually guided to good and his life ends in good. Among the actions that lead to a good ending are: steadfastness upon Allah's law, a good inner disposition, sincerity, constant repentance and seeking forgiveness, and persistence in righteous deeds.