Are the tears that appear on a dying person due to the throes of death, or joy at Jannah (Paradise), or sadness out of fear of the Fire (Hell)? And is there any Shar'i (Islamic legal) evidence that explains this phenomenon?

The agony of death is inevitable for every soul, as Allah Almighty says: "Every soul will taste death" and "And the agony of death will come with truth. That is what you were trying to avoid." And the Prophet, peace and blessings be upon him, said: "Indeed, death has agonies." Every soul suffers from death, but the intensity of that suffering varies. It is established that the dying person sees signs of good if they are a believer, and signs of evil if they are a disbeliever. For the believer, angels with white faces descend with a shroud and embalming perfume from Paradise, and it is said to their soul: "O pure soul, come out to forgiveness from Allah and His pleasure," and it departs with ease. As for the disbeliever, angels with black faces descend to them with coarse cloth from Hellfire, and it is said to their soul: "O wicked soul, come out to Allah's wrath," and it is torn out with difficulty. As for the tears that flow from the dying person, there is no evidence for them, and their knowledge is with Allah.