Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: "Al-Fadl was older than me, and he used to seat me behind him on his mount, and I would sit in front of him." Once my brother and I rode together on a she-donkey, and we came to the Messenger of Allah (peace and blessings be upon him) while he was leading the people in prayer at Arafah. We dismounted in front of him, joined the prayer and prayed, and we left the she-donkey to graze in front of him, and he (peace and blessings be upon him) did not break his prayer.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11003