Al-Abbas and Abdullah bin Abbas (may Allah be pleased with them) narrating from al-Fadl bin Abbas (may Allah be pleased with him)

Sayyiduna Abbas bin Abd al-Muttalib (may Allah be pleased with him) narrates from his son that on the Day of Arafah, al-Fadl (bin Abbas) was riding behind the Messenger of Allah (peace and blessings be upon him), and there was a crowd of people around the Messenger of Allah (peace and blessings be upon him). When the people became very many, I thought: al-Fadl will tell me what the Messenger of Allah (peace and blessings be upon him) did. Al-Fadl (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) set off (from Arafat), and the people set off with him (peace and blessings be upon him). He (peace and blessings be upon him) was holding the rein of his camel and calling out to the people: "Keep to dignity and calm." Then when he (peace and blessings be upon him) reached Muzdalifah, he dismounted there and offered the Maghrib and Isha prayers together. Then when dawn broke he offered the morning prayer, and stayed at al-Mash'ar al-Haram in Muzdalifah. Then he (peace and blessings be upon him) set off from there and the people set off with him (peace and blessings be upon him); he (peace and blessings be upon him) was holding his camel's head and saying: "O people, keep to dignity and calm," until, when he (peace and blessings be upon him) reached the valley of Muhassir, he hastened his mount a little and began saying: "Use small pebbles."
This hadith is sahih (authentic) on the condition of the two Shaykhs, since narrators other than Abu al-Zubayr have also narrated it from Abu Ma'bad, but the two of them did not record it with these words; whereas the hadith of his brother Abdullah bin Abbas (may Allah be pleased with them both) is narrated in the "Sahihayn" through Ata and Abu Ma'bad with these words: "Keep to calm," and that he was stoning the Jamrah; but the two of them did not record this present chain.

It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that he was riding behind the Messenger of Allah (peace and blessings be upon him) on the night of Muzdalifah. When the Messenger of Allah (peace and blessings be upon him) set off from there (towards Mina), he said: "O people, keep to calm and dignity, for righteousness does not lie in making horses and camels run (fast)."