Edit: read text below if you're experiencing a continuously crashing iMessages.app. After you've fixed it, turn off text preview in settings to stop this in the future.
If your iMessages are crashing because of لُلُصّبُلُلصّبُررً ॣ ॣh ॣ ॣ 冗, then just go to your photos app, send ANY picture to whoever sent the text, or whoever you sent it to. Now open your messages. Boom. Sending a message via Siri has worked as well. Try this if you can't find the recent number, if it doesn't appear in your contacts, etc. say "Siri, send 'very funny' to my latest text". That should also fix it.
IMPORTANT IF YOU RECEIVED THE MESSAGE IN A GROUP MESSAGE, YOU MUST RESPOND TO THAT EXACT MESSAGE.
Edit: If this doesn't work, have the person who sent it to you send a photo. Still doesn't work? Go into your iMessage on a Mac if possible and delete the character texts. Retry the first and second method.
Edit 2: to everyone saying "a random number sent me the text and now I can't get back in" you can open the iMessages app and when it crashes double tap the home button and look from the app preview to see the number.
Edit 3: sending "effective. Power لُلُصّبُلُلصّبُررً ॣ ॣh ॣ ॣ 冗
Send that to someone with an iPhone it turns their phone off" Only works when they are not in the iMessages.app. Interesting.
Edit 4: IMPORTANT IF YOU RECEIVED THE MESSAGE IN A GROUP MESSAGE, YOU MUST RESPOND TO THAT EXACT MESSAGE.
