I have never seen a man more devoted to the pursuit of knowledge than Abdullah bin Mubarak. He traveled through the Syrian lands, Egypt, Yemen, and the Hijaz.
أخبرنا عبيد الله بن سعيد قال
ما رأيت رجلا أطلب للعلم من عبد الله بن المبارك الشامات ومصر واليمن والحجاز
No references are available.
[Its chain of transmission is sahih] It is found in Sunan al-Kubra, hadith no. 5262.