Al-Azraq bin Qays narrates: We were fighting the Kharijites in "al-Ahwaz" alongside al-Muhallab bin Abi Sufrah. Sayyiduna Abu Barzah al-Aslami (may Allah be pleased with him) came, holding the reins of his horse, and he began to pray. Suddenly the mount slipped from his hands and set off in the direction of the qiblah. Sayyiduna Abu Barzah (may Allah be pleased with him) went after it until he caught it, then came back walking backwards. Thereupon a Kharijite began to say: Look at this old man; he has left his prayer and gone to catch his mount. Al-Azraq said: When Sayyiduna Abu Barzah (may Allah be pleased with him) completed the prayer, he came to him and said: I have fought seven battles with the Messenger of Allah (peace and blessings be upon him), and I am an old man. Had this mount of mine gone off, I would have been in trouble; that is why I did what you saw. Al-Azraq said: We said to that man: You have reviled a Companion of the Messenger of Allah (peace and blessings be upon him); Allah will surely repay you for it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3438