Al-Imām Abū al-Farj Jamāl al-Dīn ibn al-Jawzī [d. 597 AH] said:
The cure for losing a loved one is through eight ways. The first of them is to know that [this loss] was predestined to occur. Allāh says:

مَا أَصَابَ مِن مُّصِيبَةٍ فِي الْأَرْضِ وَلَا فِي أَنفُسِكُمْ إِلَّا فِي كِتَابٍ مِّن قَبْلِ أَن نَّبْرَأَهَا ۚ إِنَّ ذَٰلِكَ عَلَى اللَّهِ يَسِيرٌ ‎﴿٢٢﴾‏

‘No disaster strikes upon the earth or among yourselves except that it is in a register before We bring it into being’
[Al-Ḥadīd 57:22]

And then [Allāh] the Exalted said:

لِّكَيْلَا تَأْسَوْا عَلَىٰ مَا فَاتَكُمْ ‎﴿٢٣﴾‏

‘In order that you not despair over what has eluded you’
[Al-Ḥadīd 57:23].

This means that catastrophes are predestined, and do not occur by coincidence as the naturalists would claim, neither is its occurrence some form of nonsensical amusement. Rather, it is the creation of the One to whom belong the wisest of commands, the most unwavering and judicious of actions.

Thus, [this loss] is borne only from the Controller of All Affairs, the Most Wise, who is above reasonless futility. [His commands] either prevent corruption, or facilitate the earning of reward, or allow a deserving punishment for a misdeed to occur. [Truly grasping these matters] allows consolation.

Source: Al-Thabāt ʿInd al-Mamāt: 29
Translated by: Riyāḍ al-Kanadī