What is the ruling on acting upon a will written in the father's handwriting in 2016, without witnesses, and which he did not inform anyone about, with some rejecting it and others accepting it?

A will is validated by testimony or by admission. Scholars have differed on its validation through writing alone, without witnesses. Imam Ahmad held that it is acceptable if the testator’s handwriting is recognized.

The will must be acted upon if it is validated and there is no proof of the testator revoking it, even if a long period has passed. The heirs are not permitted to refuse its execution.

For a will to be enforceable, it must be for one-third or less of the estate, and for a non-heir. Anything exceeding one-third or bequeathed to an heir is not enforceable unless the heirs consent.

If one of the heirs refuses to execute the will, they bear the sin for that, and the others must execute it from their share. The will takes precedence over inheritance.