What is the lawful will [waṣiyyah sharʿiyyah] and what should we do upon a person's death? And what are the mistaken customs that must be avoided because they contradict Islam?

Upon a person's passing, it is recommended to remind them of patience and a good opinion of Allah, assist them with prayer, soften their joints, supplicate for their well-being, cover their body, uncover their face for kissing, hasten their burial, inform their neighbors, sit by their grave after burial, offer condolences, and prepare food for the deceased's family, while avoiding bad customs such as wailing, setting up mourning tents, and raising one's voice when carrying the funeral bier.