Good Manners and Form (Al-Adab)
Bukhari :: Book 8 :: Volume 73 :: Hadith 148
Narrated Al-Azraq bin Qais:
We were in the city of Al-Ahwaz on the bank of a river which had dried up. Then Abu Barza Al-Aslami came riding a horse and he started praying and let his horse loose. The horse ran away, so Abu Barza interrupted his prayer and went after the horse till he caught it and brought it, and then he offered his prayer. There was a man amongst us who was (from the Khawari) having a different opinion. He came saying. "Look at this old man! He left his prayer because of a horse." On that Abu Barza came to us and said, "Since the time I left Allah's Apostle, nobody has admonished me; My house is very far from this place, and if I had carried on praying and left my horse, I could not have reached my house till night." Then Abu Barza mentioned that he had been in the company of the Prophet, and that he had seen his leniency.