From Wikipedia: https://en.wikipedia.org/wiki/Basmala
Disclaimer: I'm not a Muslim, I don't know Arabic.
Also fun is ﷺ, (https://charbase.com/fdfa-unicode-arabic-ligature-sallallaho...) which has the longest unicode decomposition IIRC.
Fun fact: it’s a single Unicode character.
The current rule seems to be that all Unicode characters count as two, except for the ranges 0–4351, 8192–8205, 8208–8223 and 8242–8247 which count as one.
[1] In case you’re wondering, I think it’s, arguably: https://twitter.com/robinhouston/status/1197294154738544641
Edit: it looks like it might count it as two characters, so that’s only 140 per tweet.
https://twitter.com/fakeunicode/status/1197282221503041537
There are several amusing examples in the thread linked from this tweet.