Surah Tauba is the the only Surah in Quran that does not start with Bismillah. While all other Surahs in Quran starts with Bismillah.
Every Muslim is curious about the fact that why every surah in Quran starts with Bismillah while Surah Tauba doesn’t start with it. The great answer is being given in Al Tirmidhi narration.
According to the Al Tirmidhi narration Ibn Abbaas (RA) had narrated that he went to Uthman ibn Affan (RA) and inquired about it.
He placed two surahs Surah Anfaal and Surah Tuaba and ask Anfaal is Mathaani while Tauba is a mieen ? Why Bismillah is not placed between these two ?
Surah Al Anfaal and Surah Al Tauba have smilar context. Surah Anfaal is one of the inidtial surah revelaved in Madinah while Surah Al Tauba was one of the last.
As their sotries and contexts were similar it is labeled that Surah al Tauba is a part of Surah al Anfaal.
But, before this thing get much described whether Surah Al Tauba is a part of Surah Anfaal or not, The Prophet (PBUH) had passed away. So still it is not confirmed yet that is it a part of surah anfaal or not.
As Muhammad PBUH told his followers to not to put Bismillah infront of Surah Tauba so the whole nation does not put Bismillah before Surah Tauba.