Musnad Ahmad 32:1900

Bahz and 'Affan narrated to us, they said: Hammam narrated to us, Qatadah narrated to us, from Anas, who said: A man came while the Prophet, peace and blessings of Allah be upon him, was in prayer, and he said: "All praise is due to Allah, much, good, and blessed praise therein." When the Prophet, peace and blessings of Allah be upon him, finished the prayer, he said: "Which of you said such and such a word?" The people remained silent. He repeated it three times. A man said: "I said it, and I intended nothing by it but good." The Prophet, peace and blessings of Allah be upon him, said: "Twelve angels rushed to it, and they did not know how to record it until they asked their Lord, and He said: 'Record it as My servant said it.'"