This quote comes from a TV series Star Wars Rebels. The scene where this moment comes from is in Season 1 Episode 2, with the title of ‘Spark of Rebellion: Part 2’ (1×02). The show is a part of the Star Wars Universe. | Star Wars Rebels is produced by Lucasfilm
Obi-Wan’s message explained: In Revenge of the Sith (movie, Episode III) Darth Vader uses Jedi beacon to send message to all Jedi to return to the temple immediately.
It is after the Order 66 went into effect, which means it would mean death for those who returned. Obi-Wan sneaks into the Jedi temple and changes the message to transmit a holo recording of himself warning the Jedi not to return.
Some Jedi then saved the message to holocrons. As of now we know Kanan Jarrus and Cere Junda have one of those.
Ezra discovers the holocron and plays the message in Rebels Season 1 Episode 2. Cere Junda plays it to Cal Kestis in the game Star Wars Jedi: Fallen Order.
Obi-Wan’s full message: The full message wasn’t played in any of the tv series, movies or games yet. But we can read the whole message in the comic book Kanan: The Last Padawan. This is the full version of the message from the comic book:
“This is Master Obi-Wan Kenobi. I regret to report that both our Jedi Order and the Republic have fallen, with the dark shadow of the Empire rising to take their place. This message is a warning and a reminder for any surviving Jedi: trust in the Force. Do not return to the Temple. That time has passed, and our future is uncertain. Avoid Coruscant. Avoid detection. Be secret… but be strong. We will each be challenged: our trust, our faith, our friendships. But we must persevere and, in time, I believe a new hope will emerge. May the Force be with you always.”