The peculiar Chashma Ayub (Spring of Job) mausoleum dates from the 12th century and has a tent-like Karakhanid-style roof. Legend has it that the prophet Job struck his staff on the ground here, causing a spring to appear whose water then cured him of his many boils and ulcers. Inside is a small museum about water management in Bukhara (more interesting than it sounds) and a tap where pilgrims drink from the spring.
Next door is a modern glass-walled memorial to the 9th-century Bukharan scholar Imam Ismail al-Bukhari. Some reports suggest that the entry fee to Chashma Ayub has risen to 10,000S in the wake of 2017's currency reforms, so check in advance.