என்று: the quotative marker (Lit. ‘having said’)

என்று (AVP of என்) is used as a quotative marker like 'that' in English. It is used in reported speech constructions, but also has a number of other meanings depending upon the context. Even though this word is made with a combination of the verb என் ‘to say’, past tense suffix and the participle marker உ, like any other AVP, this form has lost much of its original lexical meaning.

Quotative When used with verbs of speech, such as சொல் ‘say’ or கேள் ‘ask’, என்று (sp. -ண்ணு) acts as a quotative marker. Unlike in English, in Tamil the reported sentence (subordinate clause) occurs first and the reporting sentence (matrix clause; i.e. main verb) occurs at the end.

கமலா நாளைக்கு வீட்டுக்கு வருவாள் என்று ராதை சொன்னாள். (written)
கமலா நாளைக்கி வீட்டுக்கு வருவாண்ணு ராதை சொன்னா. (spoken)
Radhai said that Kamala would come home tomorrow.

யார் புத்தகம் கொண்டுவரவில்லை என்று ஆசிரியர் மாணவர்களிடம் கேட்டார்.
The teacher asked all the students who didn't bring the book.

Intention and reported thought
When the matrix clause verb (i.e. the main verb) is a verb of thought, such as நினை ‘think’, or describes mental states, என்று acts to report or describe mental states: intentions, beliefs, thoughts, etc.

நான் சொல்கிறேன் என்று தாப்பாக நினைக்காதீர்கள். நீங்கள் செய்வது கொஞ்சம் கூட எனக்குப் பிடிக்கவில்லை.
Don’t take it wrong. I don’t like a bit what you do.

அம்மா திட்டிவிட்டாளே என்று மூர்த்திக்கு ஒரே கோபம்.
Murthy is angry that his mother yelled at him.

Note on reported speech/thought in Tamil

There are a number of key differences with English reported speech/thought constructions that should be noted. First, in both reported speech and thought note that because word order is relatively free in Tamil that only the main verb needs to occur at the end of the sentence. However, the subject of the main verb can occur at the beginning of the sentence, even before the subordinate clause. For example, in the sentence below the matrix clause is italicized and the subordinate clause is not:

நேற்று ஜான் அவர்கள் அவர்களுடைய புத்தகம் கணாமல் அடித்தார்கள் என்று சொன்னார்/நினைத்தார்.
Yesterday John said/thought that she lost her book.

John said “I will see him.”
John said that he would see him.

ஜான் நான் அவரை பார்ப்பேன் என்று சொன்னார்.
ஜான் அவன் அவரை பார்ப்பார் என்று சொன்னார்.