In the Quran Allah teaches about writing will before death
Quran Chapter 5 Ayah
106 and 107
O believers! When death approaches any one of you, let two just men from among yourselves act as witnesses at the time of making your last will;
or from the non-Muslims if you are travelling through the land and the calamity of death overtakes you.
If you doubt their honesty, detain them after prayer and let them both swear by Allah:
"We will not sell our testimony for any price, even to a relative, and we will not hide the testimony which we will be giving for the sake of Allah; for we shall be sinners if we do so."
Then, if it becomes known that those two were guilty of the sin of perjury,
then let two others better qualified witnesses from among those who were deprived of their right come forward and testify upon oath,
"By Allah, our
testimony is truer than theirs. We have not transgressed in our testimony; for
we should be wrongdoers if we did so."
