Whoever from amongst you sees something abominable should modify it with his hand. If he has not strength enough to do it, then he should do it with his tongue, and if he has not strength enough to do it, then he should [wish to] change it with his heart, and that is the least of faith.

Who said the above.

Wasn't that Abu Sa'eed?

Oh...almost right. This is another hadith (saying of prophet Muhammed -peace be upon him) reported by Abu Saeed.
As per my knowledge hardly any hadith (saying of prophet - Muhammed peace be upon him) were recorded in his life time. Infact once it is mentioned that the holy prophet even did not allow people to write his sayings. (Proberbly he did not want people to mix it with Quran or someother reason. God knows best).
So later on when the effort was made to document what he said.... reference of the person who heard the 'saying/hadith' is often given in the books.
I hope you understand.