Some of those chains are weak, yet their weakness is tolerable, while others are sound in and of themselves. In any case, a mutawātir ḥadith is not required to be free of every flaw in each individual route, for its authenticity is established by their collective strength, not by any one chain alone.
As for the wording, “unless the heirs consent,” it is reported by ʿAṭāʾ al-Khurasānī from Ibn ʿAbbās, but—as al-Bayhaqī notes—ʿAṭāʾ al-Khurasānī never met Ibn ʿAbbās. The phrase is also transmitted through another route from ʿAṭāʾ al-Khurasānī via ʿIkrimah to Ibn ʿAbbās, yet ʿAṭāʾ al-Khurasānī is not strong. For that reason al-Ḥāfiẓ Ibn Ḥajar preferred the mursal (unattached) version, whereas Ibn al-Qaṭṭān judged the connected, elevated narration to be ḥasan.
Shaykh al-Albānī remarked that, according to the rules of ḥadith criticism, this additional clause should be regarded as objectionable.
What is learned from the ḥadith:
1 – In the earliest period of Islam, making a bequest to one’s relatives was obligatory; this was before the verses of inheritance were revealed. When those verses came down, that obligation was abrogated—unless the adult heirs agree—as indicated in some versions of the report: “No bequest may be made for an heir, unless the heirs consent.” The right is theirs; if they are satisfied, nothing prevents it.
2 – The ḥadith confirms the soundness and legitimacy of making a bequest, for the Lawgiver regulated and guided the practice, which shows that its basis is valid.
3 – Allah has allowed a Muslim, while alive, to allocate up to one-third of his estate—effective after his death—to avenues of charity, leaving the rest to his heirs, who are the most deserving of his kindness among his inheriting relatives, whether descendants, ascendants, or collateral kin. He must not exceed one-third in his bequest, lest he encroach upon the heirs’ shares.
4 – When he does bequeath, it should be to relatives who do not inherit from him, or to the poor, scholars, those striving in Allah’s cause, or any other channel of goodness and charity. As for the one who directs his bequest