What is the correct size and number of pebbles for stoning the جمرات?

The pebbles should be slightly larger than a chickpea (approximately 1-2 cm), as described in the hadith: نبی کریم (صلی اللہ علیہ وسلم) picked up pebbles 'like date stones' (small pebbles) for stoning (Sahih Muslim 1299). Sheikh Ibn Uthaymeen stated: 'The pebbles should be between the size of a chickpea and a date stone. Using rocks or large stones is prohibited, and using very tiny pebbles may not fulfill the obligation.' The حاجی needs: 7 pebbles for جمرات al-Aqaba on the 10th; and 21 pebbles per day for the 11th, 12th (and 13th if staying). Total: 49 pebbles minimum (70 if staying for the 13th). Collecting extra pebbles as backup is مستحب. Sheikh Ibn Baz stated: 'There is no harm in picking up a few extra pebbles in case some miss the target.' Pebbles may be collected from anywhere — there is no requirement to collect them specifically from مزدلفہ.