It was narrated that Jaabir (may Allah be pleased with him) said: I heard the Prophet (saw) say, three days before he died: “No one of you should die except thinking positively of Allah.” Narrated by Muslim (2877).

In al-Mawsoo‘ah al-Fiqhiyyah (10/220) it says:

The believer is obliged to think positively of Allah, may He be exalted, and the time when it is most essential to think positively of Allah is when calamity strikes and at the time of death.