What is the interpretation of the Hadith: "Deeds are only by their conclusions"?

Al-Bukhari narrated that the Prophet, peace and blessings be upon him, said about a man fighting the polytheists: "Whoever wishes to look at a man from the people of the Hellfire, let him look at this one." In the end, the man killed himself, and the Prophet said: "Indeed, a servant may perform deeds that appear to people as deeds of the people of Paradise, yet he is among the people of the Hellfire. And he may perform deeds that appear to people as deeds of the people of the Hellfire, yet he is among the people of Paradise. Verily, deeds are judged by their conclusions." Al-Hafiz Ibn Rajab mentioned that this indicates that the inner state may differ from the outward appearance, and that a bad ending may be due to a hidden sin, while a good ending may be due to a hidden good trait. Ibn Abi Rawad recounted the story of a man who was addicted to alcohol and died as a disbeliever, warning against sins. Indeed, endings are the inheritance of preceding actions, and this is what made the predecessors fear a bad ending. Good deeds do not benefit their doer unless he dies upon Islam.