ibn Umar · The Book of Wills

It is the duty of a Muslim who has something which is to be given as a bequest not to have it for two nights without having his will written down regarding it.

Umar acquired a land at Khaibar. He came to Allah's Apostle (ﷺ) and sought his advice in regard to it. He said: Allah's Messenger, I have acquired land in Khaibar. I have never acquired property more valuable for me than this, so what do you command me to do with it? Thereupon he (Allah's Apostle) said: If you like, you may keep the corpus intact and give its produce as Sadaqa. So 'Umar gave it as Sadaqa declaring that property…

"A man came to the Prophet and said: 'O Messenger of Allah, what kind of charity brings the greatest reward?' He said: 'To give in charity when you are healthy and feeling miserly, and fearing poverty and hoping for a long life. Do not wait until the (death rattle) reaches the throat and then say: "This is for so and so," and it nearly became the property of so and so (the heirs).'"