Musnad Abu Ya'la al-Mawsili 115:259

Zuhayr narrated to us, Affan narrated to us, Hammam narrated to us, from Qatadah, from Anas, that a man entered the mosque while the Prophet, peace and blessings of Allah be upon him, was in prayer. He said: "Praise be to Allah, a pure, blessed praise, full of blessings in it." 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 for three times. Then a man from the people 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. He said: 'Record it as My servant said it.'"