Abū Dāwūd Sulaymān ibn al-Ash`ath ibn Isḥāq ibn Bashīr ibn Shaddād ibn `Amr ibn `Imrān al-Azdī as-Sijistānī was born in the year 202 AH in Sijistan, a province in Khurasan (a region covering parts of present-day Iran and Afghanistan). He was from the Azd tribe of Yemen.
He began to travel seeking aḥādīth at a young age, and reached Baghdad in 220 AH when he was 18 years old. He traveled for the purpose of checking out the possessors of aḥādīth to ensure their reliability before accepting their narrations. His journeys in search of knowledge took him through the lands of Khurasan, Iraq, Hijaz, Sham, Egypt, and Nishapur. He was not only a muḥaddith, but also a prominent faqīh who studied extensively under Imām Aḥmad ibn Hanbal.
When Imām Abū Dāwūd compiled his Sunan, Ibrāhīm al-Ḥarbi stated: “Ḥadīth was made supple (easy) for Abū Dāwūd just as ḥadīd (steel) was made supple for the Prophet Dāwūd (as).” When the Sunan was read out to Ibn al-A`rābī, he commented: “If a man had nothing with him except for the Book of Allah, and this book (of Abū Dāwūd), he would need absolutely nothing else to go along with them.”
In compiling the Sunan, Imām Abū Dāwūd included only those aḥādīth that fall under topics of Fiqh. He included only one or two aḥādīth under each chapter to make the collection concise and easy to derive fiqh.
He occasionally summarized long aḥādīth for brevity, so that the fiqh didn't get lost in the long narration. In his Sunan, he included several aḥādīth that are mursal in instances where he did not know of a contradictory hadith with a connected chain. He did not include aḥādīth from those considered matrūk al-ḥādīth (a narrator whose aḥādīth are rejected). He included a munkar (mistaken or rejected) ḥādīth only when there were no other ḥādīth in that topic. In such cases, he clearly mentioned that the ḥādīth is munkar. He also included some weak aḥādīth in his Sunan, clearly mentioning their weakness. Al Ḥāfiẓ `Abdullāh ibn Mandah said: “Abū Dāwūd narrated weak chains of narration when he did not find anything else for the topic, because to him, weak aḥādīth were stronger than the opinions of men.” For more information on his methodology in compiling his Sunan, see his letter to the people of Makkah.
According to his student, Ibn Dāsah, Imām Abū Dāwūd said: “I have written 500,000 aḥādīth of Allah’s Messenger (saws), from which I selected 4800 of the most authentic aḥādīth for this book (the Sunan). Of these, four aḥādīth are sufficient for preserving one’s Deen:
‘Actions are judged according to intentions.’
‘Of the beauty of a person’s Islam is his leaving out that which does not concern him.’
‘None of you can be a perfect believer until he loves for his brother that which he loves for himself.’
‘The halal is clear and the haram is clear, and between these two are unclear matters. Whoever saves himself from these has saved his Deen.’”