Brewer's: All in all
He is all in all to me, that is, the dearest object of my affection. God shall be all in all means all creation shall be absorbed or gathered into God. The phrase is also used adverbially, meaning altogether, as:
Take him for all in all, I shall not look upon his like again.
Shakespeare: Hamlet, ii. 2.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894