Concept: Abu Dawud al-Sijistani is remembered for collecting and compiling sayings of Prophet Muhammad.Explanation:Abu Dawud al-Sijistani was a famous scholar of Hadith.He is best known for writing the Sunan Abu Dawud, one of the six major Hadith collections.Therefore, his greatness is due to his work as a compiler of Hadith, not simply a transmitter.Answer: B. compiler of Hadith