The Prophet (peace and blessings be upon him) said:
"Keep away from the low-lying part of the valley of Muhassir, and use small pebbles (for stoning) of the kind flicked between the fingers."
Hadith Referenceصحیح الجامع الصغیر / حرف الألف / 904
Hadith Gradingالألبانی:صحيح
Hadith Takhrij[حم هق] عن ابن عباس. الصحيحة ١٥٣٤: الطحاوي.