It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said to me on the morning of Muzdalifah: "Come here and pick up pebbles for me." I picked up some pebbles that were like date stones. The Prophet (peace and blessings be upon him) took them in his hand and said: "Yes! Pebbles should be like this. Beware of exaggeration in religion, for those before you were destroyed because of exaggeration in religion."
Hadith Referenceمسند احمد / ومن مسند بني هاشم / 1851