He said he has read that book.
He said he had read that book.
Both of these sentences are grammatically correct.
It seems there is a nuance in meaning between them. So, what is the nuance?
He said he has read that book.
He said he had read that book.
Both of these sentences are grammatically correct.
It seems there is a nuance in meaning between them. So, what is the nuance?
I've never come across the He said he has read the book kind of sentence. If you want to use Indirect Speech, I suggest you use the second sentence. The past tense always matches their counterparts (past continuous, past perfect, past perfect continuous, would), so does the present tense (present continuous, present perfect, present perfect continuous, will). This first clause of the first sentence He said is the simple past tense and the second clause, he has read, is the present perfect tense; therefore, the sentence is uncoordinated. However, the second sentence, He said (which is the simple past tense) and he had read that (the past perfect tense), matches each other.
I'm pretty sure most native speakers would let this slide if you ever said the former.