Nominative for the objective.
404. The rule for the objective form is wrongly departed from—
(1) When the object is far removed from the verb, verbal, or preposition which governs it; as, "He that can doubt whether he be anything or no, I speak not to" (he should be him, the object of to); "I saw men very like him at each of the places mentioned, but not he" (he should be him, object of saw).
(2) In the case of certain pairs of pronouns, used after verbs, verbals, and prepositions, as this from Shakespeare, "All debts are cleared between you and I" (for you and me); or this, "Let thou and I the battle try" (for thee and me, or us).
(3) By forgetting the construction, in the case of words used in apposition with the object; as, "Ask the murderer, he who has steeped his hands in the blood of another" (instead of "him who," the word being in apposition with murderer).
Exception 1, who interrogative.
405. The interrogative pronoun who may be said to have no objective form in spoken English. We regularly say, "Who did you see?" or, "Who were they talking to?" etc. The more formal "To whom were they talking?" sounds stilted in conversation, and is usually avoided.
In literary English the objective form whom is preferred for objective use; as,—
Knows he now to whom he lies under obligation?—Scott.
What doth she look on? Whom doth she behold?—Wordsworth.