حَدَّثَنِي مَالِكٌ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏"‏ مَا حَقُّ امْرِئٍ مُسْلِمٍ لَهُ شَىْءٌ يُوصَى فِيهِ يَبِيتُ لَيْلَتَيْنِ إِلاَّ وَوَصِيَّتُهُ عِنْدَهُ مَكْتُوبَةٌ ‏"‏ ‏.‏

Malik related to me from Nafi from Abdullah ibn Umar that theMessenger of Allah, may Allah bless him and grant him peace, said, "Itis the duty of a muslim man who has something to be given as a bequestnot to spend two nights without writing a will about it." Malik said, "The generally agreed-on way of doing things in ourcommunity is that when the testator writes something in health orillness as a bequest, and it has freeing slaves or things other thanthat in it, he can alter it in any way he chooses, until he is on hisdeathbed. If he prefers to abandon a bequest or change it, he can doso unless he has made a slave mudabbar (to be freed after his death).If he has made him mudabbar, there is no way to change what he hasmade mudabbar. He is allowed to change his testament because theMessenger of Allah, may Allah bless him and grant him peace, said, "Itis the duty of a muslim man who has something to be given as a bequestnot to spend two nights without writing a will about it." Malik explained, "Had the testator not been able to change his willnor what was mentioned in it about freeing slaves, each testator mightwithhold making bequests from his property, whether in freeing slavesor other than it. A man gives a bequest in his health and in histravelling." (i.e. he does not wait till his death bed ) . Malik summed up, "The way of doing things in our community about whichthere is no dispute is that he can change whatever he likes of thatexcept for the mudabbar." Translation Not Available

Book reference: Muwatta Imam Malik Book 37 Hadith 1458
Web reference: Muwatta Imam Malik Book 37 Hadith 1