Sahih Muslim
The Book Pertaining to the Merits of the Companions (Allah Be Pleased With Them) of the Holy Prophet (May Peace Be Upon Him) (Kitab Al-Fadail Al-Sahabah)
Book Number: 031 / Hadith Number: 6159
'A'isha reported that a person asked Allah's Apostle (may peace be upon him) as to who amongst the people were the best. He said: Of the generation to which I belong, then of the second generation (generation adjacent to my generation), then of the third generation (generation adjacent to the second generation).