Apology by Plato

The Apology of Socrates, written by Plato, is a Socratic dialogue of the speech of legal self-defence which Socrates spoke at his trial for impiety and corruption. In 399 BC Socrates was prosecuted, convicted, sentenced to death and executed. These events were the culmination of a long philosophical career, a career in which, without writing a word, he established himself as the figure whom all philosophers of the next few generations wished to follow.

Specifically, the Apology of Socrates is a defence against the charges of "corrupting the youth" and "not believing in the gods in whom the city believes, but in other daimonia that are novel" to Athens.
Among the primary sources about the trial and death of the philosopher Socrates (469–399 BCE), the Apology of Socrates is the dialogue that depicts the trial, and is one of four Socratic dialogues, along with Euthyphro, Phaedo, and Crito, through which Plato details the final days of the philosopher Socrates.