Al-Matalib al-'Aliyah 778 — The states of the dying person

With this same chain, it is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Indeed, the death of a believer occurs with sweat on the forehead." According to the scholars, the appearance of sweat on the forehead at the time of death is, for a believer, a sign of Allah's mercy, the expiation of sins and the raising of ranks.
[Sahih: Sunan al-Tirmidhi: 982, Sunan al-Nasa'i: 1828, Sunan Ibn Majah: 1452, Musnad Ahmad: 23012].