Indirect Speech

Direct speech can be reported in two different ways depending on the tense of the reporting verb.The latter can be in a present tense or in a past tense. Introductory present tense is used when:

  the speech being reported and its indirect version are presented almost simultaneously or within a short time span.

  reporting a statement that is usually repeated

  reporting thoughts,ideas,statements which are still valid

         ex.The Bible says...

              The instructions on how to be always young say...

Introductory past tense is much often used.The general rule applied when the reporting verb is in a past tense is one tense back.There are situations when is is much more natural to disobey the rule.

ex. I told him that I'm leaving tomorrow.

For the present moment when the statement is reported, the introductory verb expresses an action that happened in the past (told) while the reported statement expresses an action that is going to happen in the future (leaving tomorrow). The reasons behind the common shift of past simple again into past simple instead of past perfect are the same as the above stated.
One should be careful because sometimes not keeping the rule leads to ambiguities.

The frequent repetition of say and tell in reported speech could be avoided using a wide range of other verbs:

There are a lot of other verbs that could be used.