A Wasiat is an Iqrar (promise) or covenant by a person, while that person is alive, on his/her property or to complete a benefit for charity or any other reason that is allowed by Syara’ (Islamic Law), which is to take effect upon his/her death.
It is a legal document that stated instruction on how the property will be managed or distributed to the loved one after his/her passed. The wasiat can be amended as many times by the testator before that.
“It is prescribed that when death approaches any of you, if they leave something of value, a will should be made in favour of parents and immediate family with fairness. This is an obligation on those who are mindful of Allah” (Surah Al-Baqarah : 180)
Sabda Rasulullah s.a.w "Barang siapa yang meninggal dalam keadaan berwasiat maka dia meninggal diatas jalan yang benar dan sunnah, dia meninggal diatas ketaqwaan dan syahadah, dan dia meninggal dalam keadaan diampuni." (Hadis Riwayat Inbu Majah)