It is narrated from Ibn Abbas (may Allah be pleased with them) that he said: When you find a crowd at the Rukn (Hajar al-Aswad), then turn back; do not stand there.
Hadith Referenceمسند الإمام الشافعي / كتاب الحج / 954
Hadith Takhrijاسناده حسن اخرجه البيهقی : 80/5، 81 - وفى المعرفة السنن والآثار له (2935)- وعبد الرزاق (8908)۔ وابن ابي شيبة (13164)۔