Did the Messenger of Allah, peace and blessings be upon him, repeat long Hadiths so that the Companions would memorize them, or did they memorize them from a single hearing?

The Prophet (peace be upon him) was keen on teaching and educating his companions. He would repeat a word three times so it could be understood, and he would speak in concise words, not narrating at length.

It was not surprising that long hadiths were transmitted from the Prophet (peace be upon him) due to the strong memory of the Arabs.

In later times, there was a need to preserve the chain of narrators (isnad). The hadith scholars followed methods to meticulously record and preserve these chains, relying on memorization and writing, to distinguish the authentic from the weak, thus preserving the Sunnah for us in its pristine form.