Say or tell?

Both say and tell take a direct object. The object is most commonly the reported clause (the report of what someone said).

Tell normally takes an indirect object (one or more people = io) and a direct object (the reported clause = do):

The boy told [IO]us [DO]he didn’t want any money.

However, we use tell without an indirect object with words such as the truth, a lie, a joke, a story:

You should never tell a lie.

Not: … say a lie.

Come on Kevin. You’re good at telling jokes.

Say does not take an indirect object. Instead, we use a phrase with to:

And then she said to me, ‘I’m your cousin. We’ve never met before.’

Not: And then she said me …

We use tell with an indirect object and a to-infinitive to report a command or an instruction. We don’t normally use say in this way:

They told us to come back the next day.

Not: They said us to come …

They told her to wait till the doctor arrived.