Simak narrated from Ikrimah (may Allah have mercy on him) that once there was doubt about the crescent of Ramadan, and they decided that they would neither pray at night nor fast. Then a Bedouin came from the Harrah and testified that he had seen the crescent. He was brought to the Prophet (peace and blessings be upon him), and he (peace and blessings be upon him) said: "Do you affirm 'La ilaha illallah' (there is no god but Allah) and 'anni Rasulullah' (that I am the Messenger of Allah)?" He said: Yes, and he affirmed that he had seen the crescent. So he (peace and blessings be upon him) ordered Bilal (may Allah be pleased with him), and he announced that the people should pray at night and fast. [Sahih. Recorded by Abu Dawud]
Abu Dawud said: A group narrated it from Simak from Ikrimah as mursal, and no one mentioned the night prayer except Hammad bin Salamah. The Shaykh said: Abu Dawud narrated the hadith of Hammad from Musa from Hammad as mursal.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 7976