What is the prescribed size for the pebbles used in the stoning ritual?
Chapter on the Description of Hajj
Al-Mughni
Book of Hajj
Primary text
The pebbles should be similar in size to the pebbles known as Hassa al-Khadhf (gravel suitable for throwing with the fingernails). This size is described as being larger than a chickpea (hummass) but smaller than a hazelnut (bunduq). Throwing with pebbles larger than this size may be invalid based on the command specifying this measure and the prohibition against excessiveness, which destroyed previous nations. The Prophet (peace be upon him) warned against religious extremism in this regard.
Supporting text
Some scholars argue that throwing with a large stone is sufficient, although one leaves the Sunnah. Ibn 'Umar used pebbles the size of sheep droppings. Some opinions suggest validity even if the size specified is not met.