I’m curious about Islam’s position on the relevance of creating a Will. Is it required, and what should not be included in a Will?

Question

Writing a Will is recommended for a Muslim. Majority of Muslim Scholars, including the four Imams of the School of Fiqh recommend writing a Will. It becomes obligatory to write a Will if it will fulfill a right for Allah such as Zakaah or Hajj or a right for a human such as debts or deposits. The Will must never contain unlawful recommendations. In a Last Will, a person may recommend anything he or she wishes preferably containing the following:

(1) Asking the family to follow the Sunnah in the funeral process.

(2) Allocating a part (within one-third) of his estate for relatives other than the heirs.