The dictionaries unanimously include the word from in their definitions of henceforth:
e.g.
M-W: from this point on
- Henceforth, supervisors will report directly to the manager.
Cambridge: starting from this time:
- Henceforth, the said building shall be the property of Brendan Duggan.
Collins: from this time onwards
- We were finally released with a formal warning that we were henceforth barred from the base.
So it strikes me as redundant to say from henceforth. Yet I see it used a few times used in the KJV Bible. For example
KJV Luke 5:10 And Jesus said unto Simon, Fear not; from henceforth thou shalt catch men.
Not surprisingly, Shakespeare also uses it in Henry IV:
I will from henceforth rather be my Selfe,
Mighty, and to be fear'd, then my condition.
FreeDictionary records an instance in a legal text:
He said pending the coming into effect of the amendment, Chambers, from henceforth, dispenses with the requirement of such service on it.
Is there an explanation for this redundant use? English seems to me a language that avoids redundancy when it can, and henceforth can clearly stand on its own. Then, why the from in from henceforth?
Note that I am very interested in antiquated language and will not mind if the explanation includes outdated examples (I would even encourage it).
Note: I hadn't noticed it before, but I see that the same problem also occurs with other words like whence, thence and hence, or their compounds. Although they all contain the idea of from, they are seen used together with from.